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8.5.2. mysql Commands

mysql sends each SQL statement that you issue to the server to be executed. There is also a set of commands that mysql itself interprets. For a list of these commands, type help or \h at the mysql> prompt:

mysql> help

List 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. NOTE: Takes the rest of the line as
               new 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
use       (\u) Use another database. Takes database name as argument.
warnings  (\W) Show warnings after every statement.
nowarning (\w) Don't show warnings after every statement.

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.

In the delimiter command, you should avoid the use of the backslash (‘\’) character because that is the escape character for MySQL.

The edit, nopager, pager, and system commands work only in Unix.

The status command provides some information about the connection and the server you are using. If you are running in --safe-updates mode, status also prints the values for the mysql variables that affect your queries.

To log queries and their output, use the tee command. All the data displayed on the screen is appended into a given file. This can be very useful for debugging purposes also. You can enable this feature on the command line with the --tee option, or interactively with the tee command. The tee file can be disabled interactively with the notee command. Executing tee again re-enables logging. Without a parameter, the previous file is used. Note that tee flushes query results to the file after each statement, just before mysql prints its next prompt.

By using the --pager option, it is possible to browse or search query results in interactive mode with Unix programs such as less, more, or any other similar program. If you specify no value for the option, mysql checks the value of the PAGER environment variable and sets the pager to that. Output paging can be enabled interactively with the pager command and disabled with nopager. 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, or stdout if no pager was specified.

Output paging works only in Unix because it uses the popen() function, which does not exist on Windows. For Windows, the tee option can be used instead to save query output, although this is not as convenient as pager for browsing output in some situations.

Here are a few tips about the pager command:

  • 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 -S option. 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 -S option to less can 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 -S interactively within less to switch the horizontal-browse mode on and off. For more information, read the less manual page:

    shell> man less
  • 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 filesystems mounted on /dr1 and /dr2, yet still display the results onscreen via less.

You can also combine the tee and pager functions. Have a tee file enabled and pager set to less, and you are able to browse the results using the less program and still have everything appended into a file the same time. The difference between the Unix tee used with the pager command and the mysql built-in tee command is that the built-in tee works even if you do not have the Unix tee available. The built-in tee also logs everything that is printed on the screen, whereas the Unix tee used with pager does not log quite that much. Additionally, tee file logging can be turned on and off interactively from within mysql. This is useful when you want to log some queries to a file, but not others.

The default mysql> prompt can be reconfigured. The string for defining the prompt can contain the following special sequences:

Option Description
\v The server version
\d The default database
\h The server host
\p The current TCP/IP port or socket file
\u Your username
\U Your full user_name@host_name account name
\\ A literal ‘\’ backslash character
\n A newline character
\t A tab character
\ A space (a space follows the backslash)
\_ A space
\R The current time, in 24-hour military time (0-23)
\r The current time, standard 12-hour time (1-12)
\m Minutes of the current time
\y The current year, two digits
\Y The current year, four digits
\D The full current date
\s Seconds of the current time
\w The current day of the week in three-letter format (Mon, Tue, …)
\P am/pm
\o The current month in numeric format
\O The current month in three-letter format (Jan, Feb, …)
\c A counter that increments for each statement you issue
\S Semicolon
\' Single quote
\" Double quote

\’ followed by any other letter just becomes that letter.

If you specify the prompt command with no argument, mysql resets the prompt to the default of mysql>.

You can set the prompt in several ways:

  • Use an environment variable. You can set the MYSQL_PS1 environment variable to a prompt string. For example:

    shell> export MYSQL_PS1="(\[email protected]\h) [\d]> "
  • Use a command-line option. You can set the --prompt option on the command line to mysql. For example:

    shell> mysql --prompt="(\[email protected]\h) [\d]> "
    ([email protected]) [database]>
  • Use an option file. You can set the prompt option in the [mysql] group of any MySQL option file, such as /etc/my.cnf or the .my.cnf file in your home directory. For example:

    prompt=(\\[email protected]\\h) [\\d]>\\_

    In this example, note that the backslashes are doubled. If you set the prompt using the prompt option 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 allowable prompt options and the set of special escape sequences that are recognized in option files. (These sequences are listed in Section 4.3.2, “Using Option Files”.) The overlap may cause you problems if you use single backslashes. For example, \s is 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 in HH:MM:SS> format:

    prompt="\\r:\\m:\\s> "
  • Set the prompt interactively. You can change your prompt interactively by using the prompt (or \R) command. For example:

    mysql> prompt (\[email protected]\h) [\d]>\_
    PROMPT set to '(\[email protected]\h) [\d]>\_'
    (user@host) [database]>
    (user@host) [database]> prompt
    Returning to default PROMPT of mysql>

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