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mysql

mysql — the MariaDB command-line tool

Examples (TL;DR)

tldr.sh

Synopsis

mysql [options] db_name

Description

mysql is a simple SQL shell (with GNU readline capabilities). It supports interactive and non-interactive use. When used interactively, query results are presented in an ASCII-table format. When used non-interactively (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 --quick option. This forces mysql to 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 the mysql_use_result() C API function in the client/server library rather than mysql_store_result().

Using mysql is very easy. Invoke it from the prompt of your command interpreter as follows:

shell> mysql db_name

Or:

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

Then type an SQL statement, end it with “;”, \g, or \G and press Enter.

Typing Control-C causes mysql to attempt to kill the current statement. If this cannot be done, or Control-C is typed again before the statement is killed, mysql exits.

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

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

MySQL Options

mysql supports the following options, which can be specified on the command line or in the [mysql], [client], [client-server] or [client-mariadb] option file groups. mysql also supports the options for processing option files.

You can also set the following variables by using --var_name=value.

On Unix, the mysql client writes a record of executed statements to a history file. By default, this file is named .mysql_history and is created in your home directory. To specify a different file, set the value of the MYSQL_HISTFILE environment variable.

The .mysql_history 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.

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

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.
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.
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.

Here are a few tips about the pager command:

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 prompt command reconfigures the default mysql> prompt. The string for defining the prompt can contain the following special sequences.

Option Description
\c A counter that increments for each statement you issue
\D The full current date
\d The default database
\h The server host
\l The current delimiter (new in 5.1.12)
\m Minutes of the current time
\n A newline character
\O The current month in three-letter format (Jan, Feb, ...)
\o The current month in numeric format
\P am/pm
\p The current TCP/IP port or socket file
\R The current time, in 24-hour military time (0–23)
\r The current time, standard 12-hour time (1–12)
\S Semicolon
\s Seconds of the current time
\t A tab character
\U

Your full user_name@host_name account name
\u Your user name
\v The server version
\w 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
\x

x, for any “x” not listed above

You can set the prompt in several ways:

MySQL Server-Side Help

mysql> help search_string

If you provide an argument to the help command, mysql uses it as a search string to access server-side help. The proper operation of this command requires that the help tables in the mysql database be initialized with help topic information.

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

mysql> help me
Nothing found
Please try to run ´help contents´ for a list of all accessible topics

Use help contents to see a list of the help categories:

mysql> help contents
You asked for help about help category: "Contents"
For more information, type ´help <item>´, where <item> is one of the
following 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, mysql shows a list of matching topics:

mysql> help logs
Many 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 logs
Name: ´SHOW BINARY LOGS´
Description:
Syntax:
SHOW BINARY LOGS
SHOW MASTER LOGS
Lists the binary log files on the server. This statement is used as
part of the procedure described in [purge-binary-logs], that shows how
to determine which logs can be purged.
mysql> SHOW BINARY LOGS;
+---------------+-----------+
| Log_name      | File_size |
+---------------+-----------+
| binlog.000015 |    724935 |
| binlog.000016 |    733481 |
+---------------+-----------+

Executing SQL Statements from a Text File

The mysql client 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 tell mysql to read its input from that file. To do so, create a text file text_file that contains the statements you wish to execute. Then invoke mysql as shown here:

shell> mysql db_name < text_file

If you place a USE db_name statement 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 running mysql, you can execute an SQL script file using the source command or \. command:

mysql> source file_name
mysql> \. 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 invoke mysql with the --verbose option, which causes each statement to be displayed before the result that it produces.

mysql ignores Unicode byte order mark (BOM) characters at the beginning of input files. Presence of a BOM does not cause mysql to change its default character set. To do that, invoke mysql with an option such as --default-character-set=utf8.

MySQL Tips

This section describes some techniques that can help you use mysql more 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 23:29:50
time_zone: +0200
mail_from: Monty
    reply: monty@no.spam.com
  mail_to: "Thimble Smith" <tim@no.spam.com>
      sbj: UTF-8
      txt: >>>>> "Thimble" == Thimble Smith writes:
Thimble> Hi.  I think this is a good idea.  Is anyone familiar
Thimble> with UTF-8 or Unicode? Otherwise, I´ll put this on my
Thimble> TODO list and see what happens.
Yes, please do that.
Regards,
Monty
     file: inbox-jani-1
     hash: 190402944
1 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 a DELETE FROM tbl_name statement but forgotten the WHERE clause. 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-updates option, mysql issues the following statement when it connects to the MariaDB server:

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

The SET statement has the following effects:

  • You are not allowed to execute an UPDATE or DELETE statement unless you specify a key constraint in the WHERE clause or provide a LIMIT clause (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 large SELECT results to 1,000 rows unless the statement includes a LIMIT clause.
  • The server aborts multiple-table SELECT statements 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-limit and --max-join-size options:

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

Disabling mysql Auto-Reconnect

If the mysql client 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 if mysql succeeds 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 away
No connection. Trying to reconnect...
Connection id:    1
Current database: test
Query OK, 1 row affected (1.30 sec)
mysql> SELECT * FROM t;
+------+
| a    |
+------+
| NULL |
+------+
1 row in set (0.05 sec)

The @a user variable has been lost with the connection, and after the reconnection it is undefined. If it is important to have mysql terminate with an error if the connection has been lost, you can start the mysql client with the --skip-reconnect option.

Notes

1.

Bug#25946
http://bugs.mysql.com/bug.php?id=25946

See Also

For more information, please refer to the MariaDB Knowledge Base, available online at https://mariadb.com/kb/

Author

MariaDB Foundation (http://www.mariadb.org/).

Referenced By

gda-sql-5.0(1), mysql-zrm(1), mysql-zrm-abort-backup(1), mysql-zrm-backup(1), mysql-zrm-check(1), mysql-zrm-extract-backup(1), mysql-zrm-list(1), mysql-zrm-parse-binlogs(1), mysql-zrm-purge(1), mysql-zrm-restore(1), mysql-zrm-scheduler(1), mysql-zrm-verify-backup(1), sql(1).

9 May 2017 MariaDB 10.3 MariaDB Database System