\FBMYSQL\FR

If you have problems due to insufficient memory for large result sets, use the--quickoption. This forcesmysqlto retrieve results from the server a row at a time rather than retrieving the entire result set and buffering it in memory before displaying it. This is done by returning the result set using themysql_use_result()C API function in the client/server library rather thanmysql_store_result().

Note

Alternatively, MySQL Shell offers access to the X DevAPI. For details, seem[blue]MySQL Shell 8.0 (part of MySQL 8.0)m[][1].

Usingmysqlis very easy. Invoke it from the prompt of your command interpreter as follows:

shell> mysql db_name

Or:

shell> mysql --user=user_name --password db_nameEnter password: your_password

Then type an SQL statement, end it with;,\g, or\Gand press Enter.

TypingControl+Cinterrupts the current statement if there is one, or cancels any partial input line otherwise.

You can execute SQL statements in a script file (batch file) like this:

shell> mysql db_name < script.sql > output.tab

On Unix, themysqlclient logs statements executed interactively to a history file. Seethe section called "MYSQL CLIENT LOGGING". 

MYSQL CLIENT OPTIONS

mysqlsupports the following options, which can be specified on the command line or in the[mysql]and[client]groups of an option file. For information about option files used by MySQL programs, seeSection 4.2.2.2, "Using Option Files".

•--help,-?Display a help message and exit.

•--auto-rehashEnable automatic rehashing. This option is on by default, which enables database, table, and column name completion. Use--disable-auto-rehashto disable rehashing. That causesmysqlto start faster, but you must issue therehashcommand or its\#shortcut if you want to use name completion.

To complete a name, enter the first part and press Tab. If the name is unambiguous,mysqlcompletes it. Otherwise, you can press Tab again to see the possible names that begin with what you have typed so far. Completion does not occur if there is no default database.

Note
This feature requires a MySQL client that is compiled with thereadlinelibrary. Typically, thereadlinelibrary is not available on Windows.

•--auto-vertical-outputCause result sets to be displayed vertically if they are too wide for the current window, and using normal tabular format otherwise. (This applies to statements terminated by;or\G.)

•--batch,-BPrint results using tab as the column separator, with each row on a new line. With this option,mysqldoes not use the history file.

Batch mode results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the--rawoption.

•--binary-as-hexWhen this option is given,mysqldisplays binary data using hexadecimal notation (0xvalue). This occurs whether the overall output display format is tabular, vertical, HTML, or XML.

--binary-as-hexwhen enabled affects display of all binary strings, including those returned by functions such asCHAR()andUNHEX(). The following example demonistrates this using the ASCII code forA(65 decimal, 41 hexadecimal):

•--binary-as-hexdisabled:

mysql> SELECT CHAR(0x41), UNHEX('41');+------------+-------------+| CHAR(0x41) | UNHEX('41') |+------------+-------------+| A          | A           |+------------+-------------+

•--binary-as-hexdisabled:

mysql> SELECT CHAR(0x41), UNHEX('41');+------------------------+--------------------------+| CHAR(0x41)             | UNHEX('41')              |+------------------------+--------------------------+| 0x41                   | 0x41                     |+------------------------+--------------------------+

To write a binary string expression so that it displays as a character string regardless of whether--binary-as-hexis enabled, use these techniques:

•TheCHAR()function has aUSING charsetclause:

mysql> SELECT CHAR(0x41 USING utf8mb4);+--------------------------+| CHAR(0x41 USING utf8mb4) |+--------------------------+| A                        |+--------------------------+

•More generally, useCONVERT()to convert an expression to a given character set:

mysql> SELECT CONVERT(UNHEX('41') USING utf8mb4);+------------------------------------+| CONVERT(UNHEX('41') USING utf8mb4) |+------------------------------------+| A                                  |+------------------------------------+

This option was added in MySQL 5.7.19.

•--binary-modeThis option helps when processingmysqlbinlogoutput that may containBLOBvalues. By default,mysqltranslates\r\nin statement strings to\nand interprets\0as the statement terminator.--binary-modedisables both features. It also disables allmysqlcommands exceptcharsetanddelimiterin noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).

•--bind-address=ip_addressOn a computer having multiple network interfaces, use this option to select which interface to use for connecting to the MySQL server.

•--character-sets-dir=dir_nameThe directory where character sets are installed. SeeSection 10.15, "Character Set Configuration".

•--column-namesWrite column names in results.

•--column-type-infoDisplay result set metadata.

•--comments,-cWhether to strip or preserve comments in statements sent to the server. The default is--skip-comments(strip comments), enable with--comments(preserve comments).

Note
In MySQL 5.7, themysqlclient always passes optimizer hints to the server, regardless of whether this option is given. To ensure that optimizer hints are not stripped if you are using an older version of themysqlclient with a version of the server that understands optimizer hints, invokemysqlwith the--commentsoption.

Comment stripping is deprecated as of MySQL 5.7.20. This feature and the options to control it will be removed in a future MySQL release.

•--compress,-CCompress all information sent between the client and the server if possible. SeeSection 4.2.5, "Connection Compression Control".

•--connect-expired-passwordIndicate to the server that the client can handle sandbox mode if the account used to connect has an expired password. This can be useful for noninteractive invocations ofmysqlbecause normally the server disconnects noninteractive clients that attempt to connect using an account with an expired password. (SeeSection 6.2.12, "Server Handling of Expired Passwords".)

•--connect-timeout=valueThe number of seconds before connection timeout. (Default value is0.)

•--database=db_name,-D db_nameThe database to use. This is useful primarily in an option file.

•--debug[=debug_options],-# [debug_options]Write a debugging log. A typicaldebug_optionsstring isd:t:o,file_name. The default isd:t:o,/tmp/mysql.trace.

This option is available only if MySQL was built usingWITH_DEBUG. MySQL release binaries provided by Oracle arenotbuilt using this option.

•--debug-checkPrint some debugging information when the program exits.

This option is available only if MySQL was built usingWITH_DEBUG. MySQL release binaries provided by Oracle arenotbuilt using this option.

•--debug-info,-TPrint debugging information and memory and CPU usage statistics when the program exits.

This option is available only if MySQL was built usingWITH_DEBUG. MySQL release binaries provided by Oracle arenotbuilt using this option.

•--default-auth=pluginA hint about which client-side authentication plugin to use. SeeSection 6.2.13, "Pluggable Authentication".

•--default-character-set=charset_nameUsecharset_nameas the default character set for the client and connection.

This option can be useful if the operating system uses one character set and themysqlclient by default uses another. In this case, output may be formatted incorrectly. You can usually fix such issues by using this option to force the client to use the system character set instead.

For more information, seeSection 10.4, "Connection Character Sets and Collations", andSection 10.15, "Character Set Configuration".

•--defaults-extra-file=file_nameRead this option file after the global option file but (on Unix) before the user option file. If the file does not exist or is otherwise inaccessible, an error occurs.file_nameis interpreted relative to the current directory if given as a relative path name rather than a full path name.

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--defaults-file=file_nameUse only the given option file. If the file does not exist or is otherwise inaccessible, an error occurs.file_nameis interpreted relative to the current directory if given as a relative path name rather than a full path name.

Exception: Even with--defaults-file, client programs read.mylogin.cnf.

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--defaults-group-suffix=strRead not only the usual option groups, but also groups with the usual names and a suffix ofstr. For example,mysqlnormally reads the[client]and[mysql]groups. If the--defaults-group-suffix=_otheroption is given,mysqlalso reads the[client_other]and[mysql_other]groups.

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--delimiter=strSet the statement delimiter. The default is the semicolon character (;).

•--disable-named-commandsDisable named commands. Use the\*form only, or use named commands only at the beginning of a line ending with a semicolon (;).mysqlstarts with this optionenabledby default. However, even with this option, long-format commands still work from the first line. Seethe section called "MYSQL CLIENT COMMANDS".

•--enable-cleartext-pluginEnable themysql_clear_passwordcleartext authentication plugin. (SeeSection 6.4.1.6, "Client-Side Cleartext Pluggable Authentication".)

•--execute=statement,-e statementExecute the statement and quit. The default output format is like that produced with--batch. SeeSection 4.2.2.1, "Using Options on the Command Line", for some examples. With this option,mysqldoes not use the history file.

•--force,-fContinue even if an SQL error occurs.

•--get-server-public-keyRequest from the server the public key required for RSA key pair-based password exchange. This option applies to clients that authenticate with thecaching_sha2_passwordauthentication plugin. For that plugin, the server does not send the public key unless requested. This option is ignored for accounts that do not authenticate with that plugin. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

If--server-public-key-path=file_nameis given and specifies a valid public key file, it takes precedence over--get-server-public-key.

For information about thecaching_sha2_passwordplugin, seeSection 6.4.1.4, "Caching SHA-2 Pluggable Authentication".

The--get-server-public-keyoption was added in MySQL 5.7.23.

•--histignoreA list of one or more colon-separated patterns specifying statements to ignore for logging purposes. These patterns are added to the default pattern list ("*IDENTIFIED*:*PASSWORD*"). The value specified for this option affects logging of statements written to the history file, and tosyslogif the--syslogoption is given. For more information, seethe section called "MYSQL CLIENT LOGGING".

•--host=host_name,-h host_nameConnect to the MySQL server on the given host.

•--html,-HProduce HTML output.

•--ignore-spaces,-iIgnore spaces after function names. The effect of this is described in the discussion for theIGNORE_SPACESQL mode (seeSection 5.1.10, "Server SQL Modes").

•--init-command=strSQL statement to execute after connecting to the server. If auto-reconnect is enabled, the statement is executed again after reconnection occurs.

•--line-numbersWrite line numbers for errors. Disable this with--skip-line-numbers.

•--local-infile[={0|1}]By default,LOCALcapability forLOAD DATAis determined by the default compiled into the MySQL client library. To enable or disableLOCALdata loading explicitly, use the--local-infileoption. When given with no value, the option enablesLOCALdata loading. When given as--local-infile=0or--local-infile=1, the option disables or enablesLOCALdata loading.

Successful use ofLOCALload operations withinmysqlalso requires that the server permits local loading; seeSection 6.1.6, "Security Considerations for LOAD DATA LOCAL"

•--login-path=nameRead options from the named login path in the.mylogin.cnflogin path file. A"login path"is an option group containing options that specify which MySQL server to connect to and which account to authenticate as. To create or modify a login path file, use themysql_config_editorutility. Seemysql_config_editor(1).

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--max-allowed-packet=valueThe maximum size of the buffer for client/server communication. The default is 16MB, the maximum is 1GB.

•--max-join-size=valueThe automatic limit for rows in a join when using--safe-updates. (Default value is 1,000,000.)

•--named-commands,-GEnable namedmysqlcommands. Long-format commands are permitted, not just short-format commands. For example,quitand\qboth are recognized. Use--skip-named-commandsto disable named commands. Seethe section called "MYSQL CLIENT COMMANDS".

•--net-buffer-length=valueThe buffer size for TCP/IP and socket communication. (Default value is 16KB.)

•--no-auto-rehash,-AThis has the same effect as--skip-auto-rehash. See the description for--auto-rehash.

•--no-beep,-bDo not beep when errors occur.

•--no-defaultsDo not read any option files. If program startup fails due to reading unknown options from an option file,--no-defaultscan be used to prevent them from being read.

The exception is that the.mylogin.cnffile, if it exists, is read in all cases. This permits passwords to be specified in a safer way than on the command line even when--no-defaultsis used. (.mylogin.cnfis created by themysql_config_editorutility. Seemysql_config_editor(1).)

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--one-database,-oIgnore statements except those that occur while the default database is the one named on the command line. This option is rudimentary and should be used with care. Statement filtering is based only onUSEstatements.

Initially,mysqlexecutes statements in the input because specifying a databasedb_nameon the command line is equivalent to insertingUSE db_nameat the beginning of the input. Then, for eachUSEstatement encountered,mysqlaccepts or rejects following statements depending on whether the database named is the one on the command line. The content of the statements is immaterial.

Suppose thatmysqlis invoked to process this set of statements:

DELETE FROM db2.t2;USE db2;DROP TABLE db1.t1;CREATE TABLE db1.t1 (i INT);USE db1;INSERT INTO t1 (i) VALUES(1);CREATE TABLE db2.t1 (j INT);

If the command line ismysql --force --one-database db1,mysqlhandles the input as follows:

•TheDELETEstatement is executed because the default database isdb1, even though the statement names a table in a different database.

•TheDROP TABLEandCREATE TABLEstatements are not executed because the default database is notdb1, even though the statements name a table indb1.

•TheINSERTandCREATE TABLEstatements are executed because the default database isdb1, even though theCREATE TABLEstatement names a table in a different database.

•--pager[=command]Use the given command for paging query output. If the command is omitted, the default pager is the value of yourPAGERenvironment variable. Valid pagers areless,more,cat [> filename], and so forth. This option works only on Unix and only in interactive mode. To disable paging, use--skip-pager.the section called "MYSQL CLIENT COMMANDS", discusses output paging further.

•--password[=password],-p[password]The password of the MySQL account used for connecting to the server. The password value is optional. If not given,mysqlprompts for one. If given, there must beno spacebetween--password=or-pand the password following it. If no password option is specified, the default is to send no password.

Specifying a password on the command line should be considered insecure. To avoid giving the password on the command line, use an option file. SeeSection 6.1.2.1, "End-User Guidelines for Password Security".

To explicitly specify that there is no password and thatmysqlshould not prompt for one, use the--skip-passwordoption.

•--pipe,-WOn Windows, connect to the server using a named pipe. This option applies only if the server was started with thenamed_pipesystem variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by thenamed_pipe_full_access_groupsystem variable.

•--plugin-dir=dir_nameThe directory in which to look for plugins. Specify this option if the--default-authoption is used to specify an authentication plugin butmysqldoes not find it. SeeSection 6.2.13, "Pluggable Authentication".

•--port=port_num,-P port_numFor TCP/IP connections, the port number to use.

•--print-defaultsPrint the program name and all options that it gets from option files.

For additional information about this and other option-file options, seeSection 4.2.2.3, "Command-Line Options that Affect Option-File Handling".

•--prompt=format_strSet the prompt to the specified format. The default ismysql>. The special sequences that the prompt can contain are described inthe section called "MYSQL CLIENT COMMANDS".

•--protocol={TCP|SOCKET|PIPE|MEMORY}The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally result in use of a protocol other than the one you want. For details on the permissible values, seeSection 4.2.4, "Connecting to the MySQL Server Using Command Options".

•--quick,-qDo not cache each query result, print each row as it is received. This may slow down the server if the output is suspended. With this option,mysqldoes not use the history file.

•--raw,-rFor tabular output, the"boxing"around columns enables one column value to be distinguished from another. For nontabular output (such as is produced in batch mode or when the--batchor--silentoption is given), special characters are escaped in the output so they can be identified easily. Newline, tab,NUL, and backslash are written as\n,\t,\0, and\\. The--rawoption disables this character escaping.

The following example demonstrates tabular versus nontabular output and the use of raw mode to disable escaping:

% mysqlmysql> SELECT CHAR(92);+----------+| CHAR(92) |+----------+| \        |+----------+% mysql -smysql> SELECT CHAR(92);CHAR(92)\\% mysql -s -rmysql> SELECT CHAR(92);CHAR(92)\

•--reconnectIf the connection to the server is lost, automatically try to reconnect. A single reconnect attempt is made each time the connection is lost. To suppress reconnection behavior, use--skip-reconnect.

•--safe-updates,--i-am-a-dummy,-UIf this option is enabled,UPDATEandDELETEstatements that do not use a key in theWHEREclause or aLIMITclause produce an error. In addition, restrictions are placed onSELECTstatements that produce (or are estimated to produce) very large result sets. If you have set this option in an option file, you can use--skip-safe-updateson the command line to override it. For more information about this option, seeUsing Safe-Updates Mode (--safe-updates).

•--secure-authDo not send passwords to the server in old (pre-4.1) format. This prevents connections except for servers that use the newer password format.

As of MySQL 5.7.5, this option is deprecated and will be removed in a future MySQL release. It is always enabled and attempting to disable it (--skip-secure-auth,--secure-auth=0) produces an error. Before MySQL 5.7.5, this option is enabled by default but can be disabled.

Note
Passwords that use the pre-4.1 hashing method are less secure than passwords that use the native password hashing method and should be avoided. Pre-4.1 passwords are deprecated and support for them was removed in MySQL 5.7.5. For account upgrade instructions, seeSection 6.4.1.3, "Migrating Away from Pre-4.1 Password Hashing and the mysql_old_password Plugin".

•--select-limit=valueThe automatic limit forSELECTstatements when using--safe-updates. (Default value is 1,000.)

•--server-public-key-path=file_nameThe path name to a file in PEM format containing a client-side copy of the public key required by the server for RSA key pair-based password exchange. This option applies to clients that authenticate with thesha256_passwordorcaching_sha2_passwordauthentication plugin. This option is ignored for accounts that do not authenticate with one of those plugins. It is also ignored if RSA-based password exchange is not used, as is the case when the client connects to the server using a secure connection.

This option is available only if MySQL was built using OpenSSL.

For information about thesha256_passwordandcaching_sha2_passwordplugins, seeSection 6.4.1.5, "SHA-256 Pluggable Authentication", andSection 6.4.1.4, "Caching SHA-2 Pluggable Authentication".

•--shared-memory-base-name=nameOn Windows, the shared-memory name to use for connections made using shared memory to a local server. The default value isMYSQL. The shared-memory name is case-sensitive.

This option applies only if the server was started with theshared_memorysystem variable enabled to support shared-memory connections.

•--show-warningsCause warnings to be shown after each statement if there are any. This option applies to interactive and batch mode.

•--sigint-ignoreIgnoreSIGINTsignals (typically the result of typingControl+C).

Without this option, typingControl+Cinterrupts the current statement if there is one, or cancels any partial input line otherwise.

•--silent,-sSilent mode. Produce less output. This option can be given multiple times to produce less and less output.

This option results in nontabular output format and escaping of special characters. Escaping may be disabled by using raw mode; see the description for the--rawoption.

•--skip-column-names,-NDo not write column names in results.

•--skip-line-numbers,-LDo not write line numbers for errors. Useful when you want to compare result files that include error messages.

•--socket=path,-S pathFor connections tolocalhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.

On Windows, this option applies only if the server was started with thenamed_pipesystem variable enabled to support named-pipe connections. In addition, the user making the connection must be a member of the Windows group specified by thenamed_pipe_full_access_groupsystem variable.

•--ssl*Options that begin with--sslspecify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. Seethe section called "Command Options for Encrypted Connections".

•--syslog,-jThis option causesmysqlto send interactive statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile.

Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line.

Mar  7 12:39:25 myhost MysqlClient[20824]:  SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,  DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar  7 12:39:28 myhost MysqlClient[20824]:  SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,  DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'

For more information, seethe section called "MYSQL CLIENT LOGGING".

•--table,-tDisplay output in table format. This is the default for interactive use, but can be used to produce table output in batch mode.

•--tee=file_nameAppend a copy of output to the given file. This option works only in interactive mode.the section called "MYSQL CLIENT COMMANDS", discusses tee files further.

•--tls-version=protocol_listThe permissible TLS protocols for encrypted connections. The value is a list of one or more comma-separated protocol names. The protocols that can be named for this option depend on the SSL library used to compile MySQL. For details, seeSection 6.3.2, "Encrypted Connection TLS Protocols and Ciphers".

This option was added in MySQL 5.7.10.

•--unbuffered,-nFlush the buffer after each query.

•--user=user_name,-u user_nameThe user name of the MySQL account to use for connecting to the server.

•--verbose,-vVerbose mode. Produce more output about what the program does. This option can be given multiple times to produce more and more output. (For example,-v -v -vproduces table output format even in batch mode.)

•--version,-VDisplay version information and exit.

•--vertical,-EPrint query output rows vertically (one line per column value). Without this option, you can specify vertical output for individual statements by terminating them with\G.

•--wait,-wIf the connection cannot be established, wait and retry instead of aborting.

•--xml,-XProduce XML output.

<field name="column_name">NULL</field>

The output when--xmlis used withmysqlmatches that ofmysqldump--xml. Seemysqldump(1), for details.

The XML output also uses an XML namespace, as shown here:

shell> mysql --xml -uroot -e "SHOW VARIABLES LIKE 'version%'"<?xml version="1.0"?><resultset statement="SHOW VARIABLES LIKE 'version%'" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"><row><field name="Variable_name">version</field><field name="Value">5.0.40-debug</field></row><row><field name="Variable_name">version_comment</field><field name="Value">Source distribution</field></row><row><field name="Variable_name">version_compile_machine</field><field name="Value">i686</field></row><row><field name="Variable_name">version_compile_os</field><field name="Value">suse-linux-gnu</field></row></resultset>

MYSQL CLIENT COMMANDS

mysqlsends each SQL statement that you issue to the server to be executed. There is also a set of commands thatmysqlitself interprets. For a list of these commands, typehelpor\hat themysql>prompt:

mysql> helpList of all MySQL commands:Note that all text commands must be first on line and end with ';'?         (\?) Synonym for `help'.clear     (\c) Clear the current input statement.connect   (\r) Reconnect to the server. Optional arguments are db and host.delimiter (\d) Set statement delimiter.edit      (\e) Edit command with $EDITOR.ego       (\G) Send command to mysql server, display result vertically.exit      (\q) Exit mysql. Same as quit.go        (\g) Send command to mysql server.help      (\h) Display this help.nopager   (\n) Disable pager, print to stdout.notee     (\t) Don't write into outfile.pager     (\P) Set PAGER [to_pager]. Print the query results via PAGER.print     (\p) Print current command.prompt    (\R) Change your mysql prompt.quit      (\q) Quit mysql.rehash    (\#) Rebuild completion hash.source    (\.) Execute an SQL script file. Takes a file name as an argument.status    (\s) Get status information from the server.system    (\!) Execute a system shell command.tee       (\T) Set outfile [to_outfile]. Append everything into given               outfile.use       (\u) Use another database. Takes database name as argument.charset   (\C) Switch to another charset. Might be needed for processing               binlog with multi-byte charsets.warnings  (\W) Show warnings after every statement.nowarning (\w) Don't show warnings after every statement.resetconnection(\x) Clean session context.For server side help, type 'help contents'

Ifmysqlis invoked with the--binary-modeoption, allmysqlcommands are disabled exceptcharsetanddelimiterin noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).

Each command has both a long and short form. The long form is not case-sensitive; the short form is. The long form can be followed by an optional semicolon terminator, but the short form should not.

The use of short-form commands within multiple-line/* ... */comments is not supported. Short-form commands do work within single-line/*! ... */version comments, as do/*+ ... */optimizer-hint comments, which are stored in object definitions. If there is a concern that optimizer-hint comments may be stored in object definitions so that dump files when reloaded withmysqlwould result in execution of such commands, either invokemysqlwith the--binary-modeoption or use a reload client other thanmysql.

•help [arg],\h [arg],\? [arg],? [arg]

Display a help message listing the availablemysqlcommands.

If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. For more information, seethe section called "MYSQL CLIENT SERVER-SIDE HELP".

•charset charset_name,\C charset_name

Change the default character set and issue aSET NAMESstatement. This enables the character set to remain synchronized on the client and server ifmysqlis run with auto-reconnect enabled (which is not recommended), because the specified character set is used for reconnects.

•clear,\c

Clear the current input. Use this if you change your mind about executing the statement that you are entering.

•connect [db_name [host_name]],\r [db_name [host_name]]

Reconnect to the server. The optional database name and host name arguments may be given to specify the default database or the host where the server is running. If omitted, the current values are used.

•delimiter str,\d str

Change the string thatmysqlinterprets as the separator between SQL statements. The default is the semicolon character (;).

The delimiter string can be specified as an unquoted or quoted argument on thedelimitercommand line. Quoting can be done with either single quote ('), double quote ("), or backtick (`) characters. To include a quote within a quoted string, either quote the string with a different quote character or escape the quote with a backslash (\) character. Backslash should be avoided outside of quoted strings because it is the escape character for MySQL. For an unquoted argument, the delimiter is read up to the first space or end of line. For a quoted argument, the delimiter is read up to the matching quote on the line.

mysqlinterprets instances of the delimiter string as a statement delimiter anywhere it occurs, except within quoted strings. Be careful about defining a delimiter that might occur within other words. For example, if you define the delimiter asX, you will be unable to use the wordINDEXin statements.mysqlinterprets this asINDEfollowed by the delimiterX.

When the delimiter recognized bymysqlis set to something other than the default of;, instances of that character are sent to the server without interpretation. However, the server itself still interprets;as a statement delimiter and processes statements accordingly. This behavior on the server side comes into play for multiple-statement execution (seeSection 27.7.15, "C API Multiple Statement Execution Support"), and for parsing the body of stored procedures and functions, triggers, and events (seeSection 23.1, "Defining Stored Programs").

•edit,\e

Edit the current input statement.mysqlchecks the values of theEDITORandVISUALenvironment variables to determine which editor to use. The default editor isviif neither variable is set.

Theeditcommand works only in Unix.

•ego,\G

Send the current statement to the server to be executed and display the result using vertical format.

•exit,\q

Exitmysql.

•go,\g

Send the current statement to the server to be executed.

•nopager,\n

Disable output paging. See the description forpager.

Thenopagercommand works only in Unix.

•notee,\t

Disable output copying to the tee file. See the description fortee.

•nowarning,\w

Disable display of warnings after each statement.

•pager [command],\P [command]

Enable output paging. By using the--pageroption when you invokemysql, it is possible to browse or search query results in interactive mode with Unix programs such asless,more, or any other similar program. If you specify no value for the option,mysqlchecks the value of thePAGERenvironment variable and sets the pager to that. Pager functionality works only in interactive mode.

Output paging can be enabled interactively with thepagercommand and disabled withnopager. The command takes an optional argument; if given, the paging program is set to that. With no argument, the pager is set to the pager that was set on the command line, orstdoutif no pager was specified.

Output paging works only in Unix because it uses thepopen()function, which does not exist on Windows. For Windows, theteeoption can be used instead to save query output, although it is not as convenient aspagerfor browsing output in some situations.

•print,\p

Print the current input statement without executing it.

•prompt [str],\R [str]

Reconfigure themysqlprompt to the given string. The special character sequences that can be used in the prompt are described later in this section.

If you specify thepromptcommand with no argument,mysqlresets the prompt to the default ofmysql>.

•quit,\q

Exitmysql.

•rehash,\#

Rebuild the completion hash that enables database, table, and column name completion while you are entering statements. (See the description for the--auto-rehashoption.)

•resetconnection,\x

Reset the connection to clear the session state.

Resetting a connection has effects similar tomysql_change_user()or an auto-reconnect except that the connection is not closed and reopened, and re-authentication is not done. SeeSection 27.7.6.3, "mysql_change_user()", andSection 27.7.19, "C API Automatic Reconnection Control".

This example shows howresetconnectionclears a value maintained in the session state:

mysql> SELECT LAST_INSERT_ID(3);+-------------------+| LAST_INSERT_ID(3) |+-------------------+|                 3 |+-------------------+mysql> SELECT LAST_INSERT_ID();+------------------+| LAST_INSERT_ID() |+------------------+|                3 |+------------------+mysql> resetconnection;mysql> SELECT LAST_INSERT_ID();+------------------+| LAST_INSERT_ID() |+------------------+|                0 |+------------------+

•source file_name,\. file_name

Read the named file and executes the statements contained therein. On Windows, specify path name separators as/or\\.

Quote characters are taken as part of the file name itself. For best results, the name should not include space characters.

•status,\s

Provide status information about the connection and the server you are using. If you are running with--safe-updatesenabled,statusalso prints the values for themysqlvariables that affect your queries.

•system command,\! command

Execute the given command using your default command interpreter.

Thesystemcommand works only in Unix.

•tee [file_name],\T [file_name]

By using the--teeoption when you invokemysql, you can log statements and their output. All the data displayed on the screen is appended into a given file. This can be very useful for debugging purposes also.mysqlflushes results to the file after each statement, just before it prints its next prompt. Tee functionality works only in interactive mode.

You can enable this feature interactively with theteecommand. Without a parameter, the previous file is used. Theteefile can be disabled with thenoteecommand. Executingteeagain re-enables logging.

•use db_name,\u db_name

Usedb_nameas the default database.

•warnings,\W

Enable display of warnings after each statement (if there are any).

Here are a few tips about thepagercommand:

•You can use it to write to a file and the results go only to the file:

mysql> pager cat > /tmp/log.txt

You can also pass any options for the program that you want to use as your pager:

mysql> pager less -n -i -S

•In the preceding example, note the-Soption. You may find it very useful for browsing wide query results. Sometimes a very wide result set is difficult to read on the screen. The-Soption tolesscan make the result set much more readable because you can scroll it horizontally using the left-arrow and right-arrow keys. You can also use-Sinteractively withinlessto switch the horizontal-browse mode on and off. For more information, read thelessmanual page:

shell> man less

•The-Fand-Xoptions may be used withlessto cause it to exit if output fits on one screen, which is convenient when no scrolling is necessary:

mysql> pager less -n -i -S -F -X

•You can specify very complex pager commands for handling query output:

mysql> pager cat | tee /dr1/tmp/res.txt \          | tee /dr2/tmp/res2.txt | less -n -i -S

In this example, the command would send query results to two files in two different directories on two different file systems mounted on/dr1and/dr2, yet still display the results onscreen usingless.

You can also combine theteeandpagerfunctions. Have ateefile enabled andpagerset toless, and you are able to browse the results using thelessprogram and still have everything appended into a file the same time. The difference between the Unixteeused with thepagercommand and themysqlbuilt-inteecommand is that the built-inteeworks even if you do not have the Unixteeavailable. The built-inteealso logs everything that is printed on the screen, whereas the Unixteeused withpagerdoes not log quite that much. Additionally,teefile logging can be turned on and off interactively from withinmysql. This is useful when you want to log some queries to a file, but not others.

Thepromptcommand reconfigures the defaultmysql>prompt. The string for defining the prompt can contain the following special sequences.

Option	Description
C	The current connection identifier
	A counter that increments for each statement you issue
D	The full current date
	The default database
The server hostT}T{ The current delimiterT}T{mT}:T{Minutes of the current timeT}T{T}:T{A newline characterT}T{OT}:T{The current month in three-letter format (Jan, Feb, ...)T}T{The current month in numeric formatT}T{PT}:T{am/pmT}T{ T}:T{The current TCP/IP port or socket fileT}T{RT}:T{The current time, in 24-hour military time (0-23)T}T{T}:T{The current time, standard 12-hour time (1-12)T}T{ST}:T{SemicolonT}T{T}:T{Seconds of the current timeT}T{ T}:T{A tab characterT}T{UT}:T{ Your fulluser_name@host_nameaccount nameT}T{T}:T{Your user nameT}T{The server versionT}T{The current day of the week in three-letter format (Mon, Tue, ...)T}T{YT}:T{The current year, four digitsT}T{yT}:T{The current year, two digitsT}T{_T}:T{A spaceT}T{\ T}:T{A space (a space follows the backslash)T}T{'T}:T{Single quoteT}T{T}:T{Double quoteT}T{\T}:T{A literal  backslash characterT}T{\fIxT}:T{ x, for any"x"not listed aboveT} You can set the prompt in several ways: •Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example: shell> export MYSQL_PS1="(\u@\h) [\d]> " •Use a command-line option.You can set the--promptoption on the command line tomysql. For example: shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]> •Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example: [mysql]prompt=(\\u@\\h) [\\d]>\\_ In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format: [mysql]prompt="\\r:\\m:\\s> " •Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example: mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>   MYSQL CLIENT LOGGING Themysqlclient can do these types of logging for statements executed interactively: •On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable. •On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile. The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. •How Logging Occurs •Controlling the History File •syslog Logging Characteristics How Logging Occurs For each enabled logging destination, statement logging occurs as follows: •Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption. •Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later. •mysqllogs each nonignored, nonempty statement line individually. •If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter. Consequently, an input statement that spans multiple lines can be logged twice. Consider this input: mysql> SELECT -> 'Today is' -> , -> CURDATE() -> ; In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output: SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE(); mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special: •?matches any single character. •*matches any sequence of zero or more characters. To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list. Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this: shell> mysql --histignore="*UPDATE*:*DELETE*" Controlling the History File The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History. If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again: •Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files. •Create.mysql_historyas a symbolic link to/dev/null; this need be done only once: shell> ln -s /dev/null $HOME/.mysql_history syslog Logging Characteristics If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics. Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability. Message size is limited to 1024 bytes. Messages consist of the identifierMysqlClientfollowed by these values: •SYSTEM_USER The operating system user name (login name) or--if the user is unknown. •MYSQL_USER The MySQL user name (specified with the--useroption) or--if the user is unknown. •CONNECTION_ID: The client connection identifier. This is the same as theCONNECTION_ID()function value within the session. •DB_SERVER The server host or--if the host is unknown. •DB The default database or--if no database has been selected. •QUERY The text of the logged statement. Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line. Mar 7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'   MYSQL CLIENT SERVER-SIDE HELP mysql> help search_string If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support"). If there is no match for the search string, the search fails: mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics Usehelp contentsto see a list of the help categories: mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories: Account Management Administration Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Language Structure Plugins Storage Engines Stored Routines Table Maintenance Transactions Triggers If the search string matches multiple items,mysqlshows a list of matching topics: mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics: SHOW SHOW BINARY LOGS SHOW ENGINE SHOW LOGS Use a topic as the search string to see the help entry for that topic: mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+ The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep: mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics: REPAIR TABLE REPEAT FUNCTION REPEAT LOOP REPLACE REPLACE FUNCTION   EXECUTING SQL STATEMENTS FROM A TEXT FILE Themysqlclient typically is used interactively, like this: shell> mysql db_name However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here: shell> mysql db_name < text_file If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line: shell> mysql < text_file If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command: mysql> source file_namemysql> \. file_name Sometimes you may want your script to display progress information to the user. For this you can insert statements like this: SELECT '<info_to_display>' AS ' '; The statement shown outputs<info_to_display>. You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces. mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8. For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode".  MYSQL CLIENT TIPS This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior. •Input-Line Editing •Disabling Interactive History •Unicode Support on Windows •Displaying Query Results Vertically •Using Safe-Updates Mode (--safe-updates) •Disabling mysql Auto-Reconnect •mysql Client Parser Versus Server Parser Input-Line Editing mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter. On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary). Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline. For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary): bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform. On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer. To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option. If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode. To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server: 1.Open a console window. 2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode. 3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets". With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.) To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe. Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile: [mysql]default-character-set=utf8 Displaying Query Results Vertically Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output: mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row *************************** msg_nro: 3068 date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones reply: jonesAATTexample.com mail_to: "John Smith" <smithAATTexample.com> sbj: UTF-8 txt: >>>>> "John" == John Smith writes:John> Hi. I think this is a good idea. Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones file: inbox-jani-1 hash: 1904029441 row in set (0.09 sec) Using Safe-Updates Mode (--safe-updates) For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets. The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables: SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000; TheSETstatement affects statement processing as follows: •Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example: UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1; •Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause. •Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations. To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql: mysql --safe-updates --select-limit=500 --max-join-size=10000 It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column: •Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization". •If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs. As of MySQL 5.7.25, safe-updates mode also includes these behaviors: •EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause. •When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index. •For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan. Disabling mysql Auto-Reconnect If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it: mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec) The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption. For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples: •The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled. Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled. •Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side. If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).   COPYRIGHT Copyright © 1997, 2020, Oracle and/or its affiliates. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.   NOTES 1. MySQL Shell 8.0 (part of MySQL 8.0) https://dev.mysql.com/doc/mysql-shell/8.0/en/   SEE ALSO For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at http://dev.mysql.com/doc/.  AUTHOR Oracle Corporation (http://dev.mysql.com/).	The server host
The current delimiterT}T{mT}:T{Minutes of the current timeT}T{T}:T{A newline characterT}T{OT}:T{The current month in three-letter format (Jan, Feb, ...)T}T{The current month in numeric formatT}T{PT}:T{am/pmT}T{ T}:T{The current TCP/IP port or socket fileT}T{RT}:T{The current time, in 24-hour military time (0-23)T}T{T}:T{The current time, standard 12-hour time (1-12)T}T{ST}:T{SemicolonT}T{T}:T{Seconds of the current timeT}T{ T}:T{A tab characterT}T{UT}:T{ Your fulluser_name@host_nameaccount nameT}T{T}:T{Your user nameT}T{The server versionT}T{The current day of the week in three-letter format (Mon, Tue, ...)T}T{YT}:T{The current year, four digitsT}T{yT}:T{The current year, two digitsT}T{_T}:T{A spaceT}T{\ T}:T{A space (a space follows the backslash)T}T{'T}:T{Single quoteT}T{T}:T{Double quoteT}T{\T}:T{A literal  backslash characterT}T{\fIxT}:T{ x, for any"x"not listed aboveT} You can set the prompt in several ways: •Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example: shell> export MYSQL_PS1="(\u@\h) [\d]> " •Use a command-line option.You can set the--promptoption on the command line tomysql. For example: shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]> •Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example: [mysql]prompt=(\\u@\\h) [\\d]>\\_ In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format: [mysql]prompt="\\r:\\m:\\s> " •Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example: mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>   MYSQL CLIENT LOGGING Themysqlclient can do these types of logging for statements executed interactively: •On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable. •On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile. The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. •How Logging Occurs •Controlling the History File •syslog Logging Characteristics How Logging Occurs For each enabled logging destination, statement logging occurs as follows: •Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption. •Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later. •mysqllogs each nonignored, nonempty statement line individually. •If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter. Consequently, an input statement that spans multiple lines can be logged twice. Consider this input: mysql> SELECT -> 'Today is' -> , -> CURDATE() -> ; In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output: SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE(); mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special: •?matches any single character. •*matches any sequence of zero or more characters. To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list. Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this: shell> mysql --histignore="*UPDATE*:*DELETE*" Controlling the History File The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History. If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again: •Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files. •Create.mysql_historyas a symbolic link to/dev/null; this need be done only once: shell> ln -s /dev/null $HOME/.mysql_history syslog Logging Characteristics If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics. Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability. Message size is limited to 1024 bytes. Messages consist of the identifierMysqlClientfollowed by these values: •SYSTEM_USER The operating system user name (login name) or--if the user is unknown. •MYSQL_USER The MySQL user name (specified with the--useroption) or--if the user is unknown. •CONNECTION_ID: The client connection identifier. This is the same as theCONNECTION_ID()function value within the session. •DB_SERVER The server host or--if the host is unknown. •DB The default database or--if no database has been selected. •QUERY The text of the logged statement. Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line. Mar 7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'   MYSQL CLIENT SERVER-SIDE HELP mysql> help search_string If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support"). If there is no match for the search string, the search fails: mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics Usehelp contentsto see a list of the help categories: mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories: Account Management Administration Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Language Structure Plugins Storage Engines Stored Routines Table Maintenance Transactions Triggers If the search string matches multiple items,mysqlshows a list of matching topics: mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics: SHOW SHOW BINARY LOGS SHOW ENGINE SHOW LOGS Use a topic as the search string to see the help entry for that topic: mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+ The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep: mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics: REPAIR TABLE REPEAT FUNCTION REPEAT LOOP REPLACE REPLACE FUNCTION   EXECUTING SQL STATEMENTS FROM A TEXT FILE Themysqlclient typically is used interactively, like this: shell> mysql db_name However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here: shell> mysql db_name < text_file If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line: shell> mysql < text_file If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command: mysql> source file_namemysql> \. file_name Sometimes you may want your script to display progress information to the user. For this you can insert statements like this: SELECT '<info_to_display>' AS ' '; The statement shown outputs<info_to_display>. You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces. mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8. For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode".  MYSQL CLIENT TIPS This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior. •Input-Line Editing •Disabling Interactive History •Unicode Support on Windows •Displaying Query Results Vertically •Using Safe-Updates Mode (--safe-updates) •Disabling mysql Auto-Reconnect •mysql Client Parser Versus Server Parser Input-Line Editing mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter. On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary). Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline. For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary): bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform. On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer. To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option. If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode. To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server: 1.Open a console window. 2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode. 3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets". With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.) To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe. Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile: [mysql]default-character-set=utf8 Displaying Query Results Vertically Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output: mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row *************************** msg_nro: 3068 date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones reply: jonesAATTexample.com mail_to: "John Smith" <smithAATTexample.com> sbj: UTF-8 txt: >>>>> "John" == John Smith writes:John> Hi. I think this is a good idea. Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones file: inbox-jani-1 hash: 1904029441 row in set (0.09 sec) Using Safe-Updates Mode (--safe-updates) For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets. The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables: SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000; TheSETstatement affects statement processing as follows: •Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example: UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1; •Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause. •Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations. To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql: mysql --safe-updates --select-limit=500 --max-join-size=10000 It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column: •Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization". •If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs. As of MySQL 5.7.25, safe-updates mode also includes these behaviors: •EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause. •When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index. •For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan. Disabling mysql Auto-Reconnect If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it: mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec) The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption. For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples: •The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled. Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled. •Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side. If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).   COPYRIGHT Copyright © 1997, 2020, Oracle and/or its affiliates. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.   NOTES 4MySQL Shell 8.0 (part of MySQL 8.0) https://dev.mysql.com/doc/mysql-shell/8.0/en/   SEE ALSO For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at http://dev.mysql.com/doc/.  AUTHOR Oracle Corporation (http://dev.mysql.com/).	The current delimiter
m	Minutes of the current time
	A newline character
O	The current month in three-letter format (Jan, Feb, ...)
The current month in numeric formatT}T{PT}:T{am/pmT}T{ T}:T{The current TCP/IP port or socket fileT}T{RT}:T{The current time, in 24-hour military time (0-23)T}T{T}:T{The current time, standard 12-hour time (1-12)T}T{ST}:T{SemicolonT}T{T}:T{Seconds of the current timeT}T{ T}:T{A tab characterT}T{UT}:T{ Your fulluser_name@host_nameaccount nameT}T{T}:T{Your user nameT}T{The server versionT}T{The current day of the week in three-letter format (Mon, Tue, ...)T}T{YT}:T{The current year, four digitsT}T{yT}:T{The current year, two digitsT}T{_T}:T{A spaceT}T{\ T}:T{A space (a space follows the backslash)T}T{'T}:T{Single quoteT}T{T}:T{Double quoteT}T{\T}:T{A literal  backslash characterT}T{\fIxT}:T{ x, for any"x"not listed aboveT} You can set the prompt in several ways: •Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example: shell> export MYSQL_PS1="(\u@\h) [\d]> " •Use a command-line option.You can set the--promptoption on the command line tomysql. For example: shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]> •Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example: [mysql]prompt=(\\u@\\h) [\\d]>\\_ In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format: [mysql]prompt="\\r:\\m:\\s> " •Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example: mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>   MYSQL CLIENT LOGGING Themysqlclient can do these types of logging for statements executed interactively: •On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable. •On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile. The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. •How Logging Occurs •Controlling the History File •syslog Logging Characteristics How Logging Occurs For each enabled logging destination, statement logging occurs as follows: •Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption. •Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later. •mysqllogs each nonignored, nonempty statement line individually. •If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter. Consequently, an input statement that spans multiple lines can be logged twice. Consider this input: mysql> SELECT -> 'Today is' -> , -> CURDATE() -> ; In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output: SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE(); mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special: •?matches any single character. •*matches any sequence of zero or more characters. To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list. Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this: shell> mysql --histignore="*UPDATE*:*DELETE*" Controlling the History File The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History. If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again: •Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files. •Create.mysql_historyas a symbolic link to/dev/null; this need be done only once: shell> ln -s /dev/null $HOME/.mysql_history syslog Logging Characteristics If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics. Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability. Message size is limited to 1024 bytes. Messages consist of the identifierMysqlClientfollowed by these values: •SYSTEM_USER The operating system user name (login name) or--if the user is unknown. •MYSQL_USER The MySQL user name (specified with the--useroption) or--if the user is unknown. •CONNECTION_ID: The client connection identifier. This is the same as theCONNECTION_ID()function value within the session. •DB_SERVER The server host or--if the host is unknown. •DB The default database or--if no database has been selected. •QUERY The text of the logged statement. Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line. Mar 7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'   MYSQL CLIENT SERVER-SIDE HELP mysql> help search_string If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support"). If there is no match for the search string, the search fails: mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics Usehelp contentsto see a list of the help categories: mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories: Account Management Administration Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Language Structure Plugins Storage Engines Stored Routines Table Maintenance Transactions Triggers If the search string matches multiple items,mysqlshows a list of matching topics: mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics: SHOW SHOW BINARY LOGS SHOW ENGINE SHOW LOGS Use a topic as the search string to see the help entry for that topic: mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+ The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep: mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics: REPAIR TABLE REPEAT FUNCTION REPEAT LOOP REPLACE REPLACE FUNCTION   EXECUTING SQL STATEMENTS FROM A TEXT FILE Themysqlclient typically is used interactively, like this: shell> mysql db_name However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here: shell> mysql db_name < text_file If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line: shell> mysql < text_file If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command: mysql> source file_namemysql> \. file_name Sometimes you may want your script to display progress information to the user. For this you can insert statements like this: SELECT '<info_to_display>' AS ' '; The statement shown outputs<info_to_display>. You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces. mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8. For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode".  MYSQL CLIENT TIPS This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior. •Input-Line Editing •Disabling Interactive History •Unicode Support on Windows •Displaying Query Results Vertically •Using Safe-Updates Mode (--safe-updates) •Disabling mysql Auto-Reconnect •mysql Client Parser Versus Server Parser Input-Line Editing mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter. On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary). Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline. For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary): bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform. On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer. To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option. If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode. To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server: 1.Open a console window. 2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode. 3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets". With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.) To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe. Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile: [mysql]default-character-set=utf8 Displaying Query Results Vertically Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output: mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row *************************** msg_nro: 3068 date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones reply: jonesAATTexample.com mail_to: "John Smith" <smithAATTexample.com> sbj: UTF-8 txt: >>>>> "John" == John Smith writes:John> Hi. I think this is a good idea. Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones file: inbox-jani-1 hash: 1904029441 row in set (0.09 sec) Using Safe-Updates Mode (--safe-updates) For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets. The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables: SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000; TheSETstatement affects statement processing as follows: •Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example: UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1; •Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause. •Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations. To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql: mysql --safe-updates --select-limit=500 --max-join-size=10000 It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column: •Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization". •If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs. As of MySQL 5.7.25, safe-updates mode also includes these behaviors: •EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause. •When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index. •For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan. Disabling mysql Auto-Reconnect If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it: mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec) The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption. For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples: •The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled. Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled. •Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side. If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).   COPYRIGHT Copyright © 1997, 2020, Oracle and/or its affiliates. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.   NOTES 1.4MySQL Shell 8.0 (part of MySQL 8.0) https://dev.mysql.com/doc/mysql-shell/8.0/en/   SEE ALSO For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at http://dev.mysql.com/doc/.  AUTHOR Oracle Corporation (http://dev.mysql.com/).	The current month in numeric format
P	am/pm
	The current TCP/IP port or socket file
R	The current time, in 24-hour military time (0-23)
	The current time, standard 12-hour time (1-12)
S	Semicolon
	Seconds of the current time
	A tab character
U	Your fulluser_name@host_nameaccount name
	Your user name
The server versionT}T{The current day of the week in three-letter format (Mon, Tue, ...)T}T{YT}:T{The current year, four digitsT}T{yT}:T{The current year, two digitsT}T{_T}:T{A spaceT}T{\ T}:T{A space (a space follows the backslash)T}T{'T}:T{Single quoteT}T{T}:T{Double quoteT}T{\T}:T{A literal  backslash characterT}T{\fIxT}:T{ x, for any"x"not listed aboveT} You can set the prompt in several ways: •Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example: shell> export MYSQL_PS1="(\u@\h) [\d]> " •Use a command-line option.You can set the--promptoption on the command line tomysql. For example: shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]> •Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example: [mysql]prompt=(\\u@\\h) [\\d]>\\_ In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format: [mysql]prompt="\\r:\\m:\\s> " •Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example: mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>   MYSQL CLIENT LOGGING Themysqlclient can do these types of logging for statements executed interactively: •On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable. •On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile. The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. •How Logging Occurs •Controlling the History File •syslog Logging Characteristics How Logging Occurs For each enabled logging destination, statement logging occurs as follows: •Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption. •Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later. •mysqllogs each nonignored, nonempty statement line individually. •If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter. Consequently, an input statement that spans multiple lines can be logged twice. Consider this input: mysql> SELECT -> 'Today is' -> , -> CURDATE() -> ; In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output: SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE(); mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special: •?matches any single character. •*matches any sequence of zero or more characters. To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list. Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this: shell> mysql --histignore="*UPDATE*:*DELETE*" Controlling the History File The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History. If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again: •Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files. •Create.mysql_historyas a symbolic link to/dev/null; this need be done only once: shell> ln -s /dev/null $HOME/.mysql_history syslog Logging Characteristics If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics. Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability. Message size is limited to 1024 bytes. Messages consist of the identifierMysqlClientfollowed by these values: •SYSTEM_USER The operating system user name (login name) or--if the user is unknown. •MYSQL_USER The MySQL user name (specified with the--useroption) or--if the user is unknown. •CONNECTION_ID: The client connection identifier. This is the same as theCONNECTION_ID()function value within the session. •DB_SERVER The server host or--if the host is unknown. •DB The default database or--if no database has been selected. •QUERY The text of the logged statement. Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line. Mar 7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'   MYSQL CLIENT SERVER-SIDE HELP mysql> help search_string If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support"). If there is no match for the search string, the search fails: mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics Usehelp contentsto see a list of the help categories: mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories: Account Management Administration Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Language Structure Plugins Storage Engines Stored Routines Table Maintenance Transactions Triggers If the search string matches multiple items,mysqlshows a list of matching topics: mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics: SHOW SHOW BINARY LOGS SHOW ENGINE SHOW LOGS Use a topic as the search string to see the help entry for that topic: mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+ The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep: mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics: REPAIR TABLE REPEAT FUNCTION REPEAT LOOP REPLACE REPLACE FUNCTION   EXECUTING SQL STATEMENTS FROM A TEXT FILE Themysqlclient typically is used interactively, like this: shell> mysql db_name However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here: shell> mysql db_name < text_file If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line: shell> mysql < text_file If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command: mysql> source file_namemysql> \. file_name Sometimes you may want your script to display progress information to the user. For this you can insert statements like this: SELECT '<info_to_display>' AS ' '; The statement shown outputs<info_to_display>. You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces. mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8. For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode".  MYSQL CLIENT TIPS This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior. •Input-Line Editing •Disabling Interactive History •Unicode Support on Windows •Displaying Query Results Vertically •Using Safe-Updates Mode (--safe-updates) •Disabling mysql Auto-Reconnect •mysql Client Parser Versus Server Parser Input-Line Editing mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter. On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary). Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline. For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary): bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform. On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer. To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option. If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode. To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server: 1.Open a console window. 2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode. 3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets". With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.) To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe. Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile: [mysql]default-character-set=utf8 Displaying Query Results Vertically Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output: mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row *************************** msg_nro: 3068 date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones reply: jonesAATTexample.com mail_to: "John Smith" <smithAATTexample.com> sbj: UTF-8 txt: >>>>> "John" == John Smith writes:John> Hi. I think this is a good idea. Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones file: inbox-jani-1 hash: 1904029441 row in set (0.09 sec) Using Safe-Updates Mode (--safe-updates) For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets. The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables: SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000; TheSETstatement affects statement processing as follows: •Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example: UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1; •Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause. •Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations. To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql: mysql --safe-updates --select-limit=500 --max-join-size=10000 It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column: •Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization". •If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs. As of MySQL 5.7.25, safe-updates mode also includes these behaviors: •EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause. •When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index. •For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan. Disabling mysql Auto-Reconnect If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it: mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec) The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption. For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples: •The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled. Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled. •Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side. If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).   COPYRIGHT Copyright © 1997, 2020, Oracle and/or its affiliates. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.   NOTES 1.4MySQL Shell 8.0 (part of MySQL 8.0) https://dev.mysql.com/doc/mysql-shell/8.0/en/   SEE ALSO For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at http://dev.mysql.com/doc/.  AUTHOR Oracle Corporation (http://dev.mysql.com/).	The server version
The current day of the week in three-letter format (Mon, Tue, ...)T}T{YT}:T{The current year, four digitsT}T{yT}:T{The current year, two digitsT}T{_T}:T{A spaceT}T{\ T}:T{A space (a space follows the backslash)T}T{'T}:T{Single quoteT}T{T}:T{Double quoteT}T{\T}:T{A literal  backslash characterT}T{\fIxT}:T{ x, for any"x"not listed aboveT} You can set the prompt in several ways: •Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example: shell> export MYSQL_PS1="(\u@\h) [\d]> " •Use a command-line option.You can set the--promptoption on the command line tomysql. For example: shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]> •Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example: [mysql]prompt=(\\u@\\h) [\\d]>\\_ In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format: [mysql]prompt="\\r:\\m:\\s> " •Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example: mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>   MYSQL CLIENT LOGGING Themysqlclient can do these types of logging for statements executed interactively: •On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable. •On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile. The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type. •How Logging Occurs •Controlling the History File •syslog Logging Characteristics How Logging Occurs For each enabled logging destination, statement logging occurs as follows: •Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption. •Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later. •mysqllogs each nonignored, nonempty statement line individually. •If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter. Consequently, an input statement that spans multiple lines can be logged twice. Consider this input: mysql> SELECT -> 'Today is' -> , -> CURDATE() -> ; In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output: SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE(); mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special: •?matches any single character. •*matches any sequence of zero or more characters. To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list. Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this: shell> mysql --histignore="*UPDATE*:*DELETE*" Controlling the History File The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History. If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again: •Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files. •Create.mysql_historyas a symbolic link to/dev/null; this need be done only once: shell> ln -s /dev/null $HOME/.mysql_history syslog Logging Characteristics If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics. Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability. Message size is limited to 1024 bytes. Messages consist of the identifierMysqlClientfollowed by these values: •SYSTEM_USER The operating system user name (login name) or--if the user is unknown. •MYSQL_USER The MySQL user name (specified with the--useroption) or--if the user is unknown. •CONNECTION_ID: The client connection identifier. This is the same as theCONNECTION_ID()function value within the session. •DB_SERVER The server host or--if the host is unknown. •DB The default database or--if no database has been selected. •QUERY The text of the logged statement. Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line. Mar 7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar 7 12:39:28 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'   MYSQL CLIENT SERVER-SIDE HELP mysql> help search_string If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support"). If there is no match for the search string, the search fails: mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics Usehelp contentsto see a list of the help categories: mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories: Account Management Administration Data Definition Data Manipulation Data Types Functions Functions and Modifiers for Use with GROUP BY Geographic Features Language Structure Plugins Storage Engines Stored Routines Table Maintenance Transactions Triggers If the search string matches multiple items,mysqlshows a list of matching topics: mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics: SHOW SHOW BINARY LOGS SHOW ENGINE SHOW LOGS Use a topic as the search string to see the help entry for that topic: mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name | File_size |+---------------+-----------+| binlog.000015 | 724935 || binlog.000016 | 733481 |+---------------+-----------+ The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep: mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics: REPAIR TABLE REPEAT FUNCTION REPEAT LOOP REPLACE REPLACE FUNCTION   EXECUTING SQL STATEMENTS FROM A TEXT FILE Themysqlclient typically is used interactively, like this: shell> mysql db_name However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here: shell> mysql db_name < text_file If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line: shell> mysql < text_file If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command: mysql> source file_namemysql> \. file_name Sometimes you may want your script to display progress information to the user. For this you can insert statements like this: SELECT '<info_to_display>' AS ' '; The statement shown outputs<info_to_display>. You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces. mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8. For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode".  MYSQL CLIENT TIPS This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior. •Input-Line Editing •Disabling Interactive History •Unicode Support on Windows •Displaying Query Results Vertically •Using Safe-Updates Mode (--safe-updates) •Disabling mysql Auto-Reconnect •mysql Client Parser Versus Server Parser Input-Line Editing mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter. On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary). Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline. For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary): bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform. On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer. To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option. If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode. To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server: 1.Open a console window. 2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode. 3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets". With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.) To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe. Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile: [mysql]default-character-set=utf8 Displaying Query Results Vertically Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output: mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row *************************** msg_nro: 3068 date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones reply: jonesAATTexample.com mail_to: "John Smith" <smithAATTexample.com> sbj: UTF-8 txt: >>>>> "John" == John Smith writes:John> Hi. I think this is a good idea. Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones file: inbox-jani-1 hash: 1904029441 row in set (0.09 sec) Using Safe-Updates Mode (--safe-updates) For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets. The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables: SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000; TheSETstatement affects statement processing as follows: •Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example: UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1; •Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause. •Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations. To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql: mysql --safe-updates --select-limit=500 --max-join-size=10000 It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column: •Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization". •If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs. As of MySQL 5.7.25, safe-updates mode also includes these behaviors: •EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause. •When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index. •For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan. Disabling mysql Auto-Reconnect If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it: mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id: 1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a |+------+| NULL |+------+1 row in set (0.05 sec) The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption. For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples: •The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled. Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled. •Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side. If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).   COPYRIGHT Copyright © 1997, 2020, Oracle and/or its affiliates. This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.   NOTES 1.4MySQL Shell 8.0 (part of MySQL 8.0) https://dev.mysql.com/doc/mysql-shell/8.0/en/   SEE ALSO For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at http://dev.mysql.com/doc/.  AUTHOR Oracle Corporation (http://dev.mysql.com/).	The current day of the week in three-letter format (Mon, Tue, ...)
Y	The current year, four digits
y	The current year, two digits
_	A space
\	A space (a space follows the backslash)
'	Single quote
	Double quote
\	A literal  backslash character
\fIx	x, for any"x"not listed above

You can set the prompt in several ways:

•Use an environment variable.You can set theMYSQL_PS1environment variable to a prompt string. For example:

shell> export MYSQL_PS1="(\u@\h) [\d]> "

•Use a command-line option.You can set the--promptoption on the command line tomysql. For example:

shell> mysql --prompt="(\u@\h) [\d]> "(userAATThost) [database]>

•Use an option file.You can set thepromptoption in the[mysql]group of any MySQL option file, such as/etc/my.cnfor the.my.cnffile in your home directory. For example:

[mysql]prompt=(\\u@\\h) [\\d]>\\_

In this example, note that the backslashes are doubled. If you set the prompt using thepromptoption in an option file, it is advisable to double the backslashes when using the special prompt options. There is some overlap in the set of permissible prompt options and the set of special escape sequences that are recognized in option files. (The rules for escape sequences in option files are listed inSection 4.2.2.2, "Using Option Files".) The overlap may cause you problems if you use single backslashes. For example,\sis interpreted as a space rather than as the current seconds value. The following example shows how to define a prompt within an option file to include the current time inhh:mm:ss>format:

[mysql]prompt="\\r:\\m:\\s> "

•Set the prompt interactively.You can change your prompt interactively by using theprompt(or\R) command. For example:

mysql> prompt (\u@\h) [\d]>\_PROMPT set to '(\u@\h) [\d]>\_'(user@host) [database]>(user@host) [database]> promptReturning to default PROMPT of mysql>mysql>

MYSQL CLIENT LOGGING

Themysqlclient can do these types of logging for statements executed interactively:

•On Unix,mysqlwrites the statements to a history file. By default, this file is named.mysql_historyin your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable.

•On all platforms, if the--syslogoption is given,mysqlwrites the statements to the system logging facility. On Unix, this issyslog; on Windows, it is the Windows Event Log. The destination where logged messages appear is system dependent. On Linux, the destination is often the/var/log/messagesfile.

The following discussion describes characteristics that apply to all logging types and provides information specific to each logging type.

•How Logging Occurs

•Controlling the History File

•syslog Logging Characteristics

For each enabled logging destination, statement logging occurs as follows:

•Statements are logged only when executed interactively. Statements are noninteractive, for example, when read from a file or a pipe. It is also possible to suppress statement logging by using the--batchor--executeoption.

•Statements are ignored and not logged if they match any pattern in the"ignore"list. This list is described later.

•mysqllogs each nonignored, nonempty statement line individually.

•If a nonignored statement spans multiple lines (not including the terminating delimiter),mysqlconcatenates the lines to form the complete statement, maps newlines to spaces, and logs the result, plus a delimiter.

Consequently, an input statement that spans multiple lines can be logged twice. Consider this input:

mysql> SELECT    -> 'Today is'    -> ,    -> CURDATE()    -> ;

In this case,mysqllogs the"SELECT","'Today is'",",","CURDATE()", and";"lines as it reads them. It also logs the complete statement, after mappingSELECT\n'Today is'\n,\nCURDATE()toSELECT 'Today is' , CURDATE(), plus a delimiter. Thus, these lines appear in logged output:

SELECT'Today is',CURDATE();SELECT 'Today is' , CURDATE();

mysqlignores for logging purposes statements that match any pattern in the"ignore"list. By default, the pattern list is"*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to passwords. Pattern matching is not case-sensitive. Within patterns, two characters are special:

•?matches any single character.

•*matches any sequence of zero or more characters.

To specify additional patterns, use the--histignoreoption or set theMYSQL_HISTIGNOREenvironment variable. (If both are specified, the option value takes precedence.) The value should be a list of one or more colon-separated patterns, which are appended to the default pattern list.

Patterns specified on the command line might need to be quoted or escaped to prevent your command interpreter from treating them specially. For example, to suppress logging forUPDATEandDELETEstatements in addition to statements that refer to passwords, invokemysqllike this:

shell> mysql --histignore="*UPDATE*:*DELETE*"

Controlling the History File

The.mysql_historyfile should be protected with a restrictive access mode because sensitive information might be written to it, such as the text of SQL statements that contain passwords. SeeSection 6.1.2.1, "End-User Guidelines for Password Security". Statements in the file are accessible from themysqlclient when theup-arrowkey is used to recall the history. SeeDisabling Interactive History.

If you do not want to maintain a history file, first remove.mysql_historyif it exists. Then use either of the following techniques to prevent it from being created again:

•Set theMYSQL_HISTFILEenvironment variable to/dev/null. To cause this setting to take effect each time you log in, put it in one of your shell's startup files.

•Create.mysql_historyas a symbolic link to/dev/null; this need be done only once:

shell> ln -s /dev/null $HOME/.mysql_history

If the--syslogoption is given,mysqlwrites interactive statements to the system logging facility. Message logging has the following characteristics.

Logging occurs at the"information"level. This corresponds to theLOG_INFOpriority forsyslogon Unix/Linuxsyslogcapability and toEVENTLOG_INFORMATION_TYPEfor the Windows Event Log. Consult your system documentation for configuration of your logging capability.

Message size is limited to 1024 bytes.

Messages consist of the identifierMysqlClientfollowed by these values:

•SYSTEM_USER

The operating system user name (login name) or--if the user is unknown.

•MYSQL_USER

The MySQL user name (specified with the--useroption) or--if the user is unknown.

•CONNECTION_ID:

The client connection identifier. This is the same as theCONNECTION_ID()function value within the session.

•DB_SERVER

The server host or--if the host is unknown.

•DB

The default database or--if no database has been selected.

•QUERY

The text of the logged statement.

Here is a sample of output generated on Linux by using--syslog. This output is formatted for readability; each logged message actually takes a single line.

Mar  7 12:39:25 myhost MysqlClient[20824]:  SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,  DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'Mar  7 12:39:28 myhost MysqlClient[20824]:  SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23,  DB_SERVER:'127.0.0.1', DB:'test', QUERY:'SHOW TABLES;'

MYSQL CLIENT SERVER-SIDE HELP

mysql> help search_string

If you provide an argument to thehelpcommand,mysqluses it as a search string to access server-side help from the contents of the MySQL Reference Manual. The proper operation of this command requires that the help tables in themysqldatabase be initialized with help topic information (seeSection 5.1.14, "Server-Side Help Support").

If there is no match for the search string, the search fails:

mysql> help meNothing foundPlease try to run 'help contents' for a list of all accessible topics

Usehelp contentsto see a list of the help categories:

mysql> help contentsYou asked for help about help category: "Contents"For more information, type 'help <item>', where <item> is one of thefollowing categories:   Account Management   Administration   Data Definition   Data Manipulation   Data Types   Functions   Functions and Modifiers for Use with GROUP BY   Geographic Features   Language Structure   Plugins   Storage Engines   Stored Routines   Table Maintenance   Transactions   Triggers

If the search string matches multiple items,mysqlshows a list of matching topics:

mysql> help logsMany help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the following topics:   SHOW   SHOW BINARY LOGS   SHOW ENGINE   SHOW LOGS

Use a topic as the search string to see the help entry for that topic:

mysql> help show binary logsName: 'SHOW BINARY LOGS'Description:Syntax:SHOW BINARY LOGSSHOW MASTER LOGSLists the binary log files on the server. This statement is used aspart of the procedure described in [purge-binary-logs], that shows howto determine which logs can be purged.mysql> SHOW BINARY LOGS;+---------------+-----------+| Log_name      | File_size |+---------------+-----------+| binlog.000015 |    724935 || binlog.000016 |    733481 |+---------------+-----------+

The search string can contain the wildcard characters%and_. These have the same meaning as for pattern-matching operations performed with theLIKEoperator. For example,HELP rep%returns a list of topics that begin withrep:

mysql> HELP rep%Many help items for your request exist.To make a more specific request, please type 'help <item>',where <item> is one of the followingtopics:   REPAIR TABLE   REPEAT FUNCTION   REPEAT LOOP   REPLACE   REPLACE FUNCTION

EXECUTING SQL STATEMENTS FROM A TEXT FILE

Themysqlclient typically is used interactively, like this:

shell> mysql db_name

However, it is also possible to put your SQL statements in a file and then tellmysqlto read its input from that file. To do so, create a text filetext_filethat contains the statements you wish to execute. Then invokemysqlas shown here:

shell> mysql db_name < text_file

If you place aUSE db_namestatement as the first statement in the file, it is unnecessary to specify the database name on the command line:

shell> mysql < text_file

If you are already runningmysql, you can execute an SQL script file using thesourcecommand or\.command:

mysql> source file_namemysql> \. file_name

Sometimes you may want your script to display progress information to the user. For this you can insert statements like this:

SELECT '<info_to_display>' AS ' ';

The statement shown outputs<info_to_display>.

You can also invokemysqlwith the--verboseoption, which causes each statement to be displayed before the result that it produces.

mysqlignores Unicode byte order mark (BOM) characters at the beginning of input files. Previously, it read them and sent them to the server, resulting in a syntax error. Presence of a BOM does not causemysqlto change its default character set. To do that, invokemysqlwith an option such as--default-character-set=utf8.

For more information about batch mode, seeSection 3.5, "Using mysql in Batch Mode". 

MYSQL CLIENT TIPS

This section provides information about techniques for more effective use ofmysqland aboutmysqloperational behavior.

•Input-Line Editing

•Disabling Interactive History

•Unicode Support on Windows

•Displaying Query Results Vertically

•Using Safe-Updates Mode (--safe-updates)

•Disabling mysql Auto-Reconnect

•mysql Client Parser Versus Server Parser

mysqlsupports input-line editing, which enables you to modify the current input line in place or recall previous input lines. For example, theleft-arrowandright-arrowkeys move horizontally within the current input line, and theup-arrowanddown-arrowkeys move up and down through the set of previously entered lines.Backspacedeletes the character before the cursor and typing new characters enters them at the cursor position. To enter the line, pressEnter.

On Windows, the editing key sequences are the same as supported for command editing in console windows. On Unix, the key sequences depend on the input library used to buildmysql(for example, thelibeditorreadlinelibrary).

Documentation for thelibeditandreadlinelibraries is available online. To change the set of key sequences permitted by a given input library, define key bindings in the library startup file. This is a file in your home directory:.editrcforlibeditand.inputrcforreadline.

For example, inlibedit,Control+Wdeletes everything before the current cursor position andControl+Udeletes the entire line. Inreadline,Control+Wdeletes the word before the cursor andControl+Udeletes everything before the current cursor position. Ifmysqlwas built usinglibedit, a user who prefers thereadlinebehavior for these two keys can put the following lines in the.editrcfile (creating the file if necessary):

bind "^W" ed-delete-prev-wordbind "^U" vi-kill-line-prev

To see the current set of key bindings, temporarily put a line that says onlybindat the end of.editrc.mysqlwill show the bindings when it starts.Disabling Interactive History

Theup-arrowkey enables you to recall input lines from current and previous sessions. In cases where a console is shared, this behavior may be unsuitable.mysqlsupports disabling the interactive history partially or fully, depending on the host platform.

On Windows, the history is stored in memory.Alt+F7deletes all input lines stored in memory for the current history buffer. It also deletes the list of sequential numbers in front of the input lines displayed withF7and recalled (by number) withF9. New input lines entered after you pressAlt+F7repopulate the current history buffer. Clearing the buffer does not prevent logging to the Windows Event Viewer, if the--syslogoption was used to startmysql. Closing the console window also clears the current history buffer.

To disable interactive history on Unix, first delete the.mysql_historyfile, if it exists (previous entries are recalled otherwise). Then startmysqlwith the--histignore="*"option to ignore all new input lines. To re-enable the recall (and logging) behavior, restartmysqlwithout the option.

If you prevent the.mysql_historyfile from being created (seeControlling the History File) and use--histignore="*"to start themysqlclient, the interactive history recall facility is disabled fully. Alternatively, if you omit the--histignoreoption, you can recall the input lines entered during the current session.Unicode Support on Windows

Windows provides APIs based on UTF-16LE for reading from and writing to the console; themysqlclient for Windows is able to use these APIs. The Windows installer creates an item in the MySQL menu namedMySQL command line client - Unicode. This item invokes themysqlclient with properties set to communicate through the console to the MySQL server using Unicode.

To take advantage of this support manually, runmysqlwithin a console that uses a compatible Unicode font and set the default character set to a Unicode character set that is supported for communication with the server:

1.Open a console window.

2.Go to the console window properties, select the font tab, and choose Lucida Console or some other compatible Unicode font. This is necessary because console windows start by default using a DOS raster font that is inadequate for Unicode.

3.Executemysql.exewith the--default-character-set=utf8(orutf8mb4) option. This option is necessary becauseutf16leis one of the character sets that cannot be used as the client character set. Seethe section called "Impermissible Client Character Sets".

With those changes,mysqlwill use the Windows APIs to communicate with the console using UTF-16LE, and communicate with the server using UTF-8. (The menu item mentioned previously sets the font and character set as just described.)

To avoid those steps each time you runmysql, you can create a shortcut that invokesmysql.exe. The shortcut should set the console font to Lucida Console or some other compatible Unicode font, and pass the--default-character-set=utf8(orutf8mb4) option tomysql.exe.

Alternatively, create a shortcut that only sets the console font, and set the character set in the[mysql]group of yourmy.inifile:

[mysql]default-character-set=utf8

Displaying Query Results Vertically

Some query results are much more readable when displayed vertically, instead of in the usual horizontal table format. Queries can be displayed vertically by terminating the query with \G instead of a semicolon. For example, longer text values that include newlines often are much easier to read with vertical output:

mysql> SELECT * FROM mails WHERE LENGTH(txt) < 300 LIMIT 300,1\G*************************** 1. row ***************************  msg_nro: 3068     date: 2000-03-01 23:29:50time_zone: +0200mail_from: Jones    reply: jonesAATTexample.com  mail_to: "John Smith" <smithAATTexample.com>      sbj: UTF-8      txt: >>>>> "John" == John Smith writes:John> Hi.  I think this is a good idea.  Is anyone familiarJohn> with UTF-8 or Unicode? Otherwise, I'll put this on myJohn> TODO list and see what happens.Yes, please do that.Regards,Jones     file: inbox-jani-1     hash: 1904029441 row in set (0.09 sec)

Using Safe-Updates Mode (--safe-updates)

For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). Safe-updates mode is helpful for cases when you might have issued anUPDATEorDELETEstatement but forgotten theWHEREclause indicating which rows to modify. Normally, such statements update or delete all rows in the table. With--safe-updates, you can modify rows only by specifying the key values that identify them, or aLIMITclause, or both. This helps prevent accidents. Safe-updates mode also restrictsSELECTstatements that produce (or are estimated to produce) very large result sets.

The--safe-updatesoption causesmysqlto execute the following statement when it connects to the MySQL server, to set the session values of thesql_safe_updates,sql_select_limit, andmax_join_sizesystem variables:

SET sql_safe_updates=1, sql_select_limit=1000, max_join_size=1000000;

TheSETstatement affects statement processing as follows:

•Enablingsql_safe_updatescausesUPDATEandDELETEstatements to produce an error if they do not specify a key constraint in theWHEREclause, or provide aLIMITclause, or both. For example:

UPDATE tbl_name SET not_key_column=val WHERE key_column=val;UPDATE tbl_name SET not_key_column=val LIMIT 1;

•Settingsql_select_limitto 1,000 causes the server to limit allSELECTresult sets to 1,000 rows unless the statement includes aLIMITclause.

•Settingmax_join_sizeto 1,000,000 causes multiple-tableSELECTstatements to produce an error if the server estimates it must examine more than 1,000,000 row combinations.

To specify result set limits different from 1,000 and 1,000,000, you can override the defaults by using the--select-limitand--max-join-sizeoptions when you invokemysql:

mysql --safe-updates --select-limit=500 --max-join-size=10000

It is possible forUPDATEandDELETEstatements to produce an error in safe-updates mode even with a key specified in theWHEREclause, if the optimizer decides not to use the index on the key column:

•Range access on the index cannot be used if memory usage exceeds that permitted by therange_optimizer_max_mem_sizesystem variable. The optimizer then falls back to a table scan. Seethe section called "Limiting Memory Use for Range Optimization".

•If key comparisons require type conversion, the index may not be used (seeSection 8.3.1, "How MySQL Uses Indexes"). Suppose that an indexed string columnc1is compared to a numeric value usingWHERE c1 = 2222. For such comparisons, the string value is converted to a number and the operands are compared numerically (seeSection 12.2, "Type Conversion in Expression Evaluation"), preventing use of the index. If safe-updates mode is enabled, an error occurs.

As of MySQL 5.7.25, safe-updates mode also includes these behaviors:

•EXPLAINwithUPDATEandDELETEstatements does not produce safe-updates errors. This enables use ofEXPLAINplusSHOW WARNINGSto see why an index is not used, which can be helpful in cases such as when arange_optimizer_max_mem_sizeviolation or type conversion occurs and the optimizer does not use an index even though a key column was specified in theWHEREclause.

•When a safe-updates error occurs, the error message includes the first diagnostic that was produced, to provide information about the reason for failure. For example, the message may indicate that therange_optimizer_max_mem_sizevalue was exceeded or type conversion occurred, either of which can preclude use of an index.

•For multiple-table deletes and updates, an error is produced with safe updates enabled only if any target table uses a table scan.

If themysqlclient loses its connection to the server while sending a statement, it immediately and automatically tries to reconnect once to the server and send the statement again. However, even ifmysqlsucceeds in reconnecting, your first connection has ended and all your previous session objects and settings are lost: temporary tables, the autocommit mode, and user-defined and session variables. Also, any current transaction rolls back. This behavior may be dangerous for you, as in the following example where the server was shut down and restarted between the first and second statements without you knowing it:

mysql> SET @a=1;Query OK, 0 rows affected (0.05 sec)mysql> INSERT INTO t VALUES(@a);ERROR 2006: MySQL server has gone awayNo connection. Trying to reconnect...Connection id:    1Current database: testQuery OK, 1 row affected (1.30 sec)mysql> SELECT * FROM t;+------+| a    |+------+| NULL |+------+1 row in set (0.05 sec)

The@auser variable has been lost with the connection, and after the reconnection it is undefined. If it is important to havemysqlterminate with an error if the connection has been lost, you can start themysqlclient with the--skip-reconnectoption.

For more information about auto-reconnect and its effect on state information when a reconnection occurs, seeSection 27.7.19, "C API Automatic Reconnection Control".mysql Client Parser Versus Server Parser

Themysqlclient uses a parser on the client side that is not a duplicate of the complete parser used by themysqldserver on the server side. This can lead to differences in treatment of certain constructs. Examples:

•The server parser treats strings delimited by"characters as identifiers rather than as plain strings if theANSI_QUOTESSQL mode is enabled.

Themysqlclient parser does not take theANSI_QUOTESSQL mode into account. It treats strings delimited by",', and`characters the same, regardless of whetherANSI_QUOTESis enabled.

•Within/*! ... */comments, themysqlclient parser interprets short-formmysqlcommands. The server parser does not interpret them because these commands have no meaning on the server side.

If it is desirable formysqlnot to interpret short-form commands within comments, a partial workaround is to use the--binary-modeoption, which causes allmysqlcommands to be disabled except\Cand\din noninteractive mode (for input piped tomysqlor loaded using thesourcecommand).

COPYRIGHT

Copyright © 1997, 2020, Oracle and/or its affiliates.

This documentation is free software; you can redistribute it and/or modify it only under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License.

This documentation is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with the program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA or see http://www.gnu.org/licenses/.

NOTES

1.4MySQL Shell 8.0 (part of MySQL 8.0)

https://dev.mysql.com/doc/mysql-shell/8.0/en/

SEE ALSO

AUTHOR

Index

NAME

SYNOPSIS

DESCRIPTION

MYSQL CLIENT OPTIONS

MYSQL CLIENT COMMANDS

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR

MYSQL CLIENT LOGGING

MYSQL CLIENT SERVER-SIDE HELP

EXECUTING SQL STATEMENTS FROM A TEXT FILE

MYSQL CLIENT TIPS

COPYRIGHT

NOTES

SEE ALSO

AUTHOR