MAN page from Other MySQL-client-community-5.0.96-1.sles10.x86_64.rpm


Section: MySQL Database System (1)
Updated: 03/02/2012


mysql - the MySQL command-line tool 


mysql [options] db_name



is a simple SQL shell (with GNUreadlinecapabilities). It supports interactive and noninteractive use. When used interactively, query results are presented in an ASCII-table format. When used noninteractively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options.

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().

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

shell> mysql db_name


shell> mysql --user=user_name --password=your_password db_name

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

As of MySQL 5.0.25, typing Control+C causesmysqlto attempt to kill the current statement. If this cannot be done, or Control+C is typed again before the statement is killed,mysqlexits. Previously, Control+C causedmysqlto exit in all cases.

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

shell> mysql db_name < script.sql >

On Unix, themysqlclient writes a record of executed statements to a history file. Seethe section called lqMYSQL HISTORY FILErq. 


mysqlsupports the following options, which can be specified on the command line or in the[mysql]and[client]groups of an option file.mysqlalso supports the options for processing option files described atSection, lqCommand-Line Options that Affect Option-File Handlingrq.


Display a help message and exit.


Enable 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 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.


Print 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.


The directory where character sets are installed. SeeSection 9.5, lqCharacter Set Configurationrq.


Write column names in results.


Whether to preserve comments in statements sent to the server. The default is --skip-comments (discard comments), enable with --comments (preserve comments). This option was added in MySQL 5.0.52.


Compress all information sent between the client and the server if both support compression.

*--database=db_name,-D db_name

The database to use. This is useful primarily in an option file.

*--debug[=debug_options],-# [debug_options]

Write a debugging log. A typicaldebug_optionsstring is'd:t:o,file_name'. The default is'd:t:o,/tmp/mysql.trace'.


Print some debugging information when the program exits.


Usecharset_nameas the default character set for the client and connection.

A common issue that can occur when the operating system usesutf8or another multi-byte character set is that output from themysqlclient is formatted incorrectly, due to the fact that the MySQL client uses thelatin1character set by default. You can usually fix such issues by using this option to force the client to use the system character set instead.

SeeSection 9.5, lqCharacter Set Configurationrq, for more information.


Set the statement delimiter. The default is the semicolon character (lq;rq).


Disable named commands. Use the\*form only, or use named commands only at the beginning of a line ending with a semicolon (lq;rq).mysqlstarts with this optionenabledby default. However, even with this option, long-format commands still work from the first line. Seethe section called lqMYSQL COMMANDSrq.

*--execute=statement,-e statement

Execute the statement and quit. The default output format is like that produced with--batch. SeeSection, lqUsing Options on the Command Linerq, for some examples. With this option,mysqldoes not use the history file.


Continue even if an SQL error occurs.

*--host=host_name,-h host_name

Connect to the MySQL server on the given host.


Produce HTML output.


Ignore spaces after function names. The effect of this is described in the discussion for theIGNORE_SPACESQL mode (seeSection 5.1.6, lqServer SQL Modesrq).


Write line numbers for errors. Disable this with--skip-line-numbers.


Enable or disableLOCALcapability forLOAD DATA INFILE. With no value, the option enablesLOCAL. The option may be given as--local-infile=0or--local-infile=1to explicitly disable or enableLOCAL. EnablingLOCALhas no effect if the server does not also support it.


Enable 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 lqMYSQL COMMANDSrq.


This has the same effect as-skip-auto-rehash. See the description for--auto-rehash.


Do not beep when errors occur.


Deprecated, use--disable-named-commandsinstead.--no-named-commandsis removed in MySQL 5.5.


Deprecated form of--skip-pager. See the--pageroption.--no-pageris removed in MySQL 5.5.


Deprecated form of--skip-tee. See the--teeoption.--no-teeis removed in MySQL 5.5.


Ignore 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.


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 lqMYSQL COMMANDSrq, discusses output paging further.


The password to use when connecting to the server. If you use the short option form (-p), youcannothave a space between the option and the password. If you omit thepasswordvalue following the--passwordor-poption on the command line,mysqlprompts for one.

Specifying a password on the command line should be considered insecure. SeeSection, lqEnd-User Guidelines for Password Securityrq. You can use an option file to avoid giving the password on the command line.


On Windows, connect to the server using a named pipe. This option applies only if the server supports named-pipe connections.

*--port=port_num,-P port_num

The TCP/IP port number to use for the connection.


Set the prompt to the specified format. The default ismysql>. The special sequences that the prompt can contain are described inthe section called lqMYSQL COMMANDSrq.


The connection protocol to use for connecting to the server. It is useful when the other connection parameters normally would cause a protocol to be used other than the one you want. For details on the permissible values, seeSection 4.2.2, lqConnecting to the MySQL Serverrq.


Do 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.


For tabular output, thelqboxingrqaround 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)\


If 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.


Permit only thoseUPDATEandDELETEstatements that specify which rows to modify by using key values. If you have set this option in an option file, you can override it by using--safe-updateson the command line. Seethe section called lqMYSQL TIPSrq, for more information about this option.


Do not send passwords to the server in old (pre-4.1.1) format. This prevents connections except for servers that use the newer password format.


Cause warnings to be shown after each statement if there are any. This option applies to interactive and batch mode. This option was added in MySQL 5.0.6.


IgnoreSIGINTsignals (typically the result of typing Control+C).


Silent 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.


Do not write column names in results.


Do not write line numbers for errors. Useful when you want to compare result files that include error messages.

*--socket=path,-S path

For connections tolocalhost, the Unix socket file to use, or, on Windows, the name of the named pipe to use.


Options that begin with--sslspecify whether to connect to the server using SSL and indicate where to find SSL keys and certificates. SeeSection, lqSSL Command Optionsrq.


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


Append a copy of output to the given file. This option works only in interactive mode.the section called lqMYSQL COMMANDSrq, discusses tee files further.


Flush the buffer after each query.

*--user=user_name,-u user_name

The MySQL user name to use when connecting to the server.


Verbose 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.)


Display version information and exit.


Print 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.


If the connection cannot be established, wait and retry instead of aborting.


Produce XML output.

Prior to MySQL 5.0.26, there was no differentiation in the output when using this option between columns containing theNULLvalue and columns containing the string literal'NULL'; both were represented as

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

Beginning with MySQL 5.0.26, the output when--xmlis used withmysqlmatches that ofmysqldump --xml. Seemysqldump(1)for details.

Beginning with MySQL 5.0.40, 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=""><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>

(See Bug #25946.)

You can also set the following variables by using--var_name=value. The--set-variableformat is deprecated.


The number of seconds before connection timeout. (Default value is0.)


The maximum packet length to send to or receive from the server. (Default value is 16MB.)


The automatic limit for rows in a join when using--safe-updates. (Default value is 1,000,000.)


The buffer size for TCP/IP and socket communication. (Default value is 16KB.)


The automatic limit forSELECTstatements when using--safe-updates. (Default value is 1,000.)

It is also possible to set variables by using--var_name=value. The--set-variableformat is deprecated. 


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 command.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      (\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.For server side help, type 'help contents'

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 multi-line/* ... */comments is not supported.

*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 lqMYSQL SERVER-SIDE HELPrq.

*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. This command was added in MySQL 5.0.19.


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 (lq;rq).

The delimiter string can be specified as an unquoted or quoted argument on thedelimitercommand line. Quoting can be done with either single quote ('), douple 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 (lq\rq) 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 oflq;rq, instances of that character are sent to the server without interpretation. However, the server itself still interpretslq;rqas a statement delimiter and processes statements accordingly. This behavior on the server side comes into play for multiple-statement execution (seeSection 19.8.12, lqC API Support for Multiple Statement Executionrq), and for parsing the body of stored procedures and functions and triggers (seeSection 17.1, lqDefining Stored Programsrq).


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.


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

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.




Send the current statement to the server to be executed.


Disable output paging. See the description forpager.

Thenopagercommand works only in Unix.


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


Enable display of warnings after each statement. This command was added in MySQL 5.0.6.

*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 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>.




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

*source file_name,\. file_name

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


Provide status information about the connection and the server you are using. If you are running in--safe-updatesmode,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.


Enable display of warnings after each statement (if there are any). This command was added in MySQL 5.0.6.

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.
\cA counter that increments for each statement you issue
\DThe full current date
\dThe default database
\hThe server host
\lThe current delimiter (new in 5.0.25)
\mMinutes of the current time
\nA newline character
\OThe current month in three-letter format (Jan, Feb, ...)
\oThe current month in numeric format
\pThe current TCP/IP port or socket file
\RThe current time, in 24-hour military time (0-23)
\rThe current time, standard 12-hour time (1-12)
\sSeconds of the current time
\tA tab character

Your fulluser_name@host_nameaccount name

\uYour user name
\vThe server version
\wThe current day of the week in three-letter format (Mon, Tue, ...)
\YThe current year, four digits
\yThe current year, two digits
\_A space
A space (a space follows the backslash)
\'Single quote
\"Double quote
\\A literal lq\rq backslash character

x, for anylqxrqnot 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 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, lqUsing Option Filesrq.) 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>


On Unix, themysqlclient writes a record of executed statements to a history file. By default, this file is named.mysql_historyand is created in your home directory. To specify a different file, set the value of theMYSQL_HISTFILEenvironment variable.

The.mysql_historyshould 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, lqEnd-User Guidelines for Password Securityrq.

It is possible to suppress logging of statements to the history file by using the--batchor--executeoption.

If you do not want to maintain a history file, first remove.mysql_historyif it exists, and then use either of the following techniques:

*Set theMYSQL_HISTFILEvariable to/dev/null. To cause this setting to take effect each time you log in, put the setting in one of your shell's startup files.

*Create.mysql_historyas a symbolic link to/dev/null:

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

You need do this only once.



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 5.1.7, lqServer-Side Helprq).

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   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 |+---------------+-----------+


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.

As of MySQL 5.0.54,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, lqUsing mysql in Batch Moderq. 


This section describes some techniques that can help you usemysqlmore effectively. 

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: Monty    reply:  mail_to: "Thimble Smith" <>      sbj: UTF-8      txt: >>>>> "Thimble" == Thimble Smith writes:Thimble> Hi.  I think this is a good idea.  Is anyone familiarThimble> with UTF-8 or Unicode? Otherwise, I'll put this on myThimble> TODO list and see what happens.Yes, please do that.Regards,Monty     file: inbox-jani-1     hash: 1904029441 row in set (0.09 sec)

Using the --safe-updates Option

For beginners, a useful startup option is--safe-updates(or--i-am-a-dummy, which has the same effect). It is helpful for cases when you might have issued aDELETE FROM tbl_namestatement but forgotten theWHEREclause. Normally, such a statement deletes all rows from the table. With--safe-updates, you can delete rows only by specifying the key values that identify them. This helps prevent accidents.

When you use the--safe-updatesoption,mysqlissues the following statement when it connects to the MySQL server:

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

SeeSection 5.1.3, lqServer System Variablesrq.

TheSETstatement has the following effects:

*You are not permitted to execute anUPDATEorDELETEstatement unless you 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;

*The server limits all largeSELECTresults to 1,000 rows unless the statement includes aLIMITclause.

*The server aborts multiple-tableSELECTstatements that probably need to examine more than 1,000,000 row combinations.

To specify limits different from 1,000 and 1,000,000, you can override the defaults by using the--select_limitand--max_join_sizeoptions:

shell> mysql --safe-updates --select_limit=500 --max_join_size=10000

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 19.8.11, lqControlling Automatic Reconnection Behaviorrq. 


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For more information, please refer to the MySQL Reference Manual,which may already be installed locally and which is also availableonline at 


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Displaying Query Results Vertically
Using the --safe-updates Option
Disabling mysql Auto-Reconnect

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