mysql

MYSQL(1) MySQL Database System MYSQL(1)

NAME
mysql - the MySQL command-line client

SYNOPSIS
mysql [options] db_name

DESCRIPTION
mysql is a simple SQL shell with input line editing capabilities. 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 --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().

Note
Alternatively, MySQL Shell offers access to the X DevAPI. For
details, see MySQL Shell 8.0[1].

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

mysql db_name

Or:

mysql --user=user_name --password db_name

In this case, you'll need to enter your password in response to the
prompt that mysql displays:

Enter password: your_password

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

Typing Control+C interrupts 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:

mysql db_name < script.sql > output.tab

On Unix, the mysql client logs statements executed interactively to a
history file. See the section called "MYSQL CLIENT LOGGING".

MYSQL CLIENT OPTIONS
mysql supports 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, see
Section 4.2.2.2, "Using Option Files".

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

o --auto-rehash Enable automatic rehashing. This option is on by
default, which enables database, table, and column name completion.
Use --disable-auto-rehash to disable rehashing. That causes mysql
to start faster, but you must issue the rehash command 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, mysql completes 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 the
readline library. Typically, the readline library is not
available on Windows.

o --auto-vertical-output Cause 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.)

o --batch, -B Print results using tab as the column separator, with
each row on a new line. With this option, mysql does 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 --raw option.

o --binary-as-hex When this option is given, mysql displays binary
data using hexadecimal notation (0xvalue). This occurs whether the
overall output display format is tabular, vertical, HTML, or XML.

--binary-as-hex when enabled affects display of all binary strings,
including those returned by functions such as CHAR() and UNHEX().
The following example demonistrates this using the ASCII code for A
(65 decimal, 41 hexadecimal):

o --binary-as-hex disabled:

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

o --binary-as-hex enabled:

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-hex is enabled,
use these techniques:

o The CHAR() function has a USING charset clause:

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

o More generally, use CONVERT() 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.

o --binary-mode This option helps when processing mysqlbinlog output
that may contain BLOB values. By default, mysql translates \r\n in
statement strings to \n and interprets \0 as the statement
terminator. --binary-mode disables both features. It also disables
all mysql commands except charset and delimiter in noninteractive
mode (for input piped to mysql or loaded using the source command).

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

o --character-sets-dir=dir_name The directory where character sets
are installed. See Section 10.15, "Character Set Configuration".

o --column-names Write column names in results.

o --column-type-info Display result set metadata. This information
corresponds to the contents of C API MYSQL_FIELD data structures.
See C API Basic Data Structures[2].

o --comments, -c Whether 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, the mysql client 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 the mysql client with a version of the
server that understands optimizer hints, invoke mysql with the
--comments option.

Comment stripping is deprecated as of MySQL 5.7.20. You should
expect this feature and the options to control it to be removed
in a future MySQL release.

o --compress, -C Compress all information sent between the client and
the server if possible. See Section 4.2.6, "Connection Compression
Control".

o --connect-expired-password Indicate 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
of mysql because normally the server disconnects noninteractive
clients that attempt to connect using an account with an expired
password. (See Section 6.2.12, "Server Handling of Expired
Passwords".)

o --connect-timeout=value The number of seconds before connection
timeout. (Default value is 0.)

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

o --debug[=debug_options], -# [debug_options] Write a debugging log.
A typical debug_options string is d:t:o,file_name. The default is
d:t:o,/tmp/mysql.trace.

This option is available only if MySQL was built using WITH_DEBUG.
MySQL release binaries provided by Oracle are not built using this
option.

o --debug-check Print some debugging information when the program
exits.

This option is available only if MySQL was built using WITH_DEBUG.
MySQL release binaries provided by Oracle are not built using this
option.

o --debug-info, -T Print debugging information and memory and CPU
usage statistics when the program exits.

This option is available only if MySQL was built using WITH_DEBUG.
MySQL release binaries provided by Oracle are not built using this
option.

o --default-auth=plugin A hint about which client-side authentication
plugin to use. See Section 6.2.13, "Pluggable Authentication".

o --default-character-set=charset_name Use charset_name as the
default character set for the client and connection.

This option can be useful if the operating system uses one
character set and the mysql client 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, see Section 10.4, "Connection Character Sets
and Collations", and Section 10.15, "Character Set Configuration".

o --defaults-extra-file=file_name Read 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. If file_name is not an absolute path name, it is
interpreted relative to the current directory.

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

o --defaults-file=file_name Use only the given option file. If the
file does not exist or is otherwise inaccessible, an error occurs.
If file_name is not an absolute path name, it is interpreted
relative to the current directory.

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

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

o --defaults-group-suffix=str Read not only the usual option groups,
but also groups with the usual names and a suffix of str. For
example, mysql normally reads the [client] and [mysql] groups. If
this option is given as --defaults-group-suffix=_other, mysql also
reads the [client_other] and [mysql_other] groups.

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

o --delimiter=str Set the statement delimiter. The default is the
semicolon character (;).

o --disable-named-commands Disable named commands. Use the \* form
only, or use named commands only at the beginning of a line ending
with a semicolon (;). mysql starts with this option enabled by
default. However, even with this option, long-format commands still
work from the first line. See the section called "MYSQL CLIENT
COMMANDS".

o --enable-cleartext-plugin Enable the mysql_clear_password cleartext
authentication plugin. (See Section 6.4.1.6, "Client-Side Cleartext
Pluggable Authentication".)

o --execute=statement, -e statement Execute the statement and quit.
The default output format is like that produced with --batch. See
Section 4.2.2.1, "Using Options on the Command Line", for some
examples. With this option, mysql does not use the history file.

o --force, -f Continue even if an SQL error occurs.

o --get-server-public-key Request from the server the public key
required for RSA key pair-based password exchange. This option
applies to clients that authenticate with the caching_sha2_password
authentication 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_name is given and specifies a
valid public key file, it takes precedence over
--get-server-public-key.

For information about the caching_sha2_password plugin, see
Section 6.4.1.4, "Caching SHA-2 Pluggable Authentication".

The --get-server-public-key option was added in MySQL 5.7.23.

o --histignore A 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 to
syslog if the --syslog option is given. For more information, see
the section called "MYSQL CLIENT LOGGING".

o --host=host_name, -h host_name Connect to the MySQL server on the
given host.

o --html, -H Produce HTML output.

o --ignore-spaces, -i Ignore spaces after function names. The effect
of this is described in the discussion for the IGNORE_SPACE SQL
mode (see Section 5.1.10, "Server SQL Modes").

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

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

o --local-infile[={0|1}] By default, LOCAL capability for LOAD DATA
is determined by the default compiled into the MySQL client
library. To enable or disable LOCAL data loading explicitly, use
the --local-infile option. When given with no value, the option
enables LOCAL data loading. When given as --local-infile=0 or
--local-infile=1, the option disables or enables LOCAL data
loading.

Successful use of LOCAL load operations within mysql also requires
that the server permits local loading; see Section 6.1.6, "Security
Considerations for LOAD DATA LOCAL"

o --login-path=name Read options from the named login path in the
.mylogin.cnf login 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 the mysql_config_editor utility. See
mysql_config_editor(1).

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

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

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

o --named-commands, -G Enable named mysql commands. Long-format
commands are permitted, not just short-format commands. For
example, quit and \q both are recognized. Use --skip-named-commands
to disable named commands. See the section called "MYSQL CLIENT
COMMANDS".

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

o --no-auto-rehash, -A This has the same effect as
--skip-auto-rehash. See the description for --auto-rehash.

o --no-beep, -b Do not beep when errors occur.

o --no-defaults Do not read any option files. If program startup
fails due to reading unknown options from an option file,
--no-defaults can be used to prevent them from being read.

The exception is that the .mylogin.cnf file is read in all cases,
if it exists. This permits passwords to be specified in a safer way
than on the command line even when --no-defaults is used. To create
.mylogin.cnf, use the mysql_config_editor utility. See
mysql_config_editor(1).

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

o --one-database, -o 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 on USE statements.

Initially, mysql executes statements in the input because
specifying a database db_name on the command line is equivalent to
inserting USE db_name at the beginning of the input. Then, for each
USE statement encountered, mysql accepts 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 that mysql is 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 is mysql --force --one-database db1, mysql
handles the input as follows:

o The DELETE statement is executed because the default database
is db1, even though the statement names a table in a different
database.

o The DROP TABLE and CREATE TABLE statements are not executed
because the default database is not db1, even though the
statements name a table in db1.

o The INSERT and CREATE TABLE statements are executed because the
default database is db1, even though the CREATE TABLE statement
names a table in a different database.

o --pager[=command] Use the given command for paging query output. If
the command is omitted, the default pager is the value of your
PAGER environment variable. Valid pagers are less, 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.

o --password[=password], -p[password] The password of the MySQL
account used for connecting to the server. The password value is
optional. If not given, mysql prompts for one. If given, there must
be no space between --password= or -p and 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. See Section 6.1.2.1, "End-User Guidelines for Password
Security".

To explicitly specify that there is no password and that mysql
should not prompt for one, use the --skip-password option.

o --pipe, -W On Windows, connect to the server using a named pipe.
This option applies only if the server was started with the
named_pipe system variable enabled to support named-pipe
connections. In addition, the user making the connection must be a
member of the Windows group specified by the
named_pipe_full_access_group system variable.

o --plugin-dir=dir_name The directory in which to look for plugins.
Specify this option if the --default-auth option is used to specify
an authentication plugin but mysql does not find it. See
Section 6.2.13, "Pluggable Authentication".

o --port=port_num, -P port_num For TCP/IP connections, the port
number to use.

o --print-defaults Print the program name and all options that it
gets from option files.

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

o --prompt=format_str Set the prompt to the specified format. The
default is mysql>. The special sequences that the prompt can
contain are described in the section called "MYSQL CLIENT
COMMANDS".

o --protocol={TCP|SOCKET|PIPE|MEMORY} The transport 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, see
Section 4.2.5, "Connection Transport Protocols".

o --quick, -q 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, mysql does not use the history file.

o --raw, -r For 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 --batch or
--silent option 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 --raw option
disables this character escaping.

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

% mysql
mysql> SELECT CHAR(92);
+----------+
| CHAR(92) |
+----------+
| \ |
+----------+
% mysql -s
mysql> SELECT CHAR(92);
CHAR(92)
\\
% mysql -s -r
mysql> SELECT CHAR(92);
CHAR(92)
\

o --reconnect 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.

o --safe-updates, --i-am-a-dummy, -U If this option is enabled,
UPDATE and DELETE statements that do not use a key in the WHERE
clause or a LIMIT clause produce an error. In addition,
restrictions are placed on SELECT statements 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-updates on the
command line to override it. For more information about this
option, see Using Safe-Updates Mode (--safe-updates).

o --secure-auth Do 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; expect it to 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, see Section 6.4.1.3, "Migrating Away from Pre-4.1
Password Hashing and the mysql_old_password Plugin".

o --select-limit=value The automatic limit for SELECT statements when
using --safe-updates. (Default value is 1,000.)

o --server-public-key-path=file_name The 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 the sha256_password or
caching_sha2_password authentication 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.

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

For sha256_password, this option applies only if MySQL was built
using OpenSSL.

For information about the sha256_password and caching_sha2_password
plugins, see Section 6.4.1.5, "SHA-256 Pluggable Authentication",
and Section 6.4.1.4, "Caching SHA-2 Pluggable Authentication".

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

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

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

o --sigint-ignore Ignore SIGINT signals (typically the result of
typing Control+C).

Without this option, typing Control+C interrupts the current
statement if there is one, or cancels any partial input line
otherwise.

o --silent, -s 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 --raw option.

o --skip-column-names, -N Do not write column names in results.

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

o --socket=path, -S path For connections to localhost, 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
the named_pipe system variable enabled to support named-pipe
connections. In addition, the user making the connection must be a
member of the Windows group specified by the
named_pipe_full_access_group system variable.

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

o --syslog, -j This option causes mysql to send interactive
statements to the system logging facility. On Unix, this is syslog;
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/messages file.

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, see the section called "MYSQL CLIENT
LOGGING".

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

o --tee=file_name Append 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.

o --tls-version=protocol_list The 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, see Section 6.3.2, "Encrypted Connection TLS Protocols and
Ciphers".

This option was added in MySQL 5.7.10.

o --unbuffered, -n Flush the buffer after each query.

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

o --verbose, -v 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 -v produces table output
format even in batch mode.)

o --version, -V Display version information and exit.

o --vertical, -E 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.

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

o --xml, -X Produce XML output.

The output when --xml is used with mysql matches that of mysqldump
--xml. See mysqldump(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
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 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'

If mysql is invoked with the --binary-mode option, all mysql commands
are disabled except charset and delimiter in noninteractive mode (for
input piped to mysql or loaded using the source command).

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 with mysql would result in execution of such
commands, either invoke mysql with the --binary-mode option or use a
reload client other than mysql.

o help [arg], \h [arg], \? [arg], ? [arg]

Display a help message listing the available mysql commands.

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

o charset charset_name, \C charset_name

Change the default character set and issue a SET NAMES statement.
This enables the character set to remain synchronized on the client
and server if mysql is run with auto-reconnect enabled (which is
not recommended), because the specified character set is used for
reconnects.

o clear, \c

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

o 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.

o delimiter str, \d str

Change the string that mysql interprets 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 the delimiter command 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.

mysql interprets 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 as X, it is not
possible to use the word INDEX in statements. mysql interprets
this as INDE followed by the delimiter X.

When the delimiter recognized by mysql is 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 (see Multiple Statement Execution
Support[3]), and for parsing the body of stored procedures and
functions, triggers, and events (see Section 23.1, "Defining Stored
Programs").

o edit, \e

Edit the current input statement. mysql checks the values of the
EDITOR and VISUAL environment variables to determine which editor
to use. The default editor is vi if neither variable is set.

The edit command works only in Unix.

o ego, \G

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

o exit, \q

Exit mysql.

o go, \g

Send the current statement to the server to be executed.

o nopager, \n

Disable output paging. See the description for pager.

The nopager command works only in Unix.

o notee, \t

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

o nowarning, \w

Disable display of warnings after each statement.

o pager [command], \P [command]

Enable output paging. By using the --pager option when you invoke
mysql, 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. Pager functionality works only in interactive
mode.

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 it is not
as convenient as pager for browsing output in some situations.

o print, \p

Print the current input statement without executing it.

o prompt [str], \R [str]

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

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

o quit, \q

Exit mysql.

o rehash, \#

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

o resetconnection, \x

Reset the connection to clear the session state.

Resetting a connection has effects similar to mysql_change_user()
or an auto-reconnect except that the connection is not closed and
reopened, and re-authentication is not done. See
mysql_change_user()[4], and Automatic Reconnection Control[5].

This example shows how resetconnection clears 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 |
+------------------+

o 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.

o status, \s

Provide status information about the connection and the server you
are using. If you are running with --safe-updates enabled, status
also prints the values for the mysql variables that affect your
queries.

o system command, \! command

Execute the given command using your default command interpreter.

The system command works only in Unix.

o tee [file_name], \T [file_name]

By using the --tee option when you invoke mysql, 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. mysql flushes 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 the tee command.
Without a parameter, the previous file is used. The tee file can be
disabled with the notee command. Executing tee again re-enables
logging.

o use db_name, \u db_name

Use db_name as the default database.

o warnings, \W

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

Here are a few tips about the pager command:

o 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

o 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:

man less

o The -F and -X options may be used with less to 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

o 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 /dr1 and /dr2, yet still display the results onscreen using
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 prompt command reconfigures the default mysql> prompt. The string
for defining the prompt can contain the following special sequences.

r
.br
.br
72
+---------------------------+----------------------------+
|Option | Description |
+---------------------------+----------------------------+
| | The current connection |
| | identifier |
+---------------------------+----------------------------+
| | A counter that increments |
| | for each statement you |
| | issue |
+---------------------------+----------------------------+
| | The full current date |
+---------------------------+----------------------------+
| | The default database |
+---------------------------+----------------------------+
| | The server host |
+---------------------------+----------------------------+
| | The current delimiter |
+---------------------------+----------------------------+
| | Minutes of the current |
| | time |
+---------------------------+----------------------------+
| | A newline character |
+---------------------------+----------------------------+
| | The current month in |
| | three-letter format (Jan, |
| | Feb, ...) |
+---------------------------+----------------------------+
| | The current month in |
| | numeric format |
+---------------------------+----------------------------+
|P | am/pm |
+---------------------------+----------------------------+
| | The current TCP/IP port or |
| | socket file |
+---------------------------+----------------------------+
| | The current time, in |
| | 24-hour military time |
| | (0-23) |
+---------------------------+----------------------------+
| | The current time, standard |
| | 12-hour time (1-12) |
+---------------------------+----------------------------+
| | Semicolon |
+---------------------------+----------------------------+
| | Seconds of the current |
| | time |
+---------------------------+----------------------------+
| | A tab character |
+---------------------------+----------------------------+
|U | |
| | Your full |
| | user_name@host_name |
| | account name |
+---------------------------+----------------------------+
| | Your user name |
+---------------------------+----------------------------+
| | The server version |
+---------------------------+----------------------------+
| | The current day of the |
| | week in three-letter |
| | format (Mon, Tue, ...) |
+---------------------------+----------------------------+
| | The current year, four |
| | digits |
+---------------------------+----------------------------+
|y | The current year, two |
| | digits |
+---------------------------+----------------------------+
|_ | A space |
+---------------------------+----------------------------+
|\ | A space (a space follows |
| | the backslash) |
+---------------------------+----------------------------+
|' | Single quote |
+---------------------------+----------------------------+
| | Double quote |
+---------------------------+----------------------------+
|T}:T{ A literal backslash | |
|character | |
+---------------------------+----------------------------+
|\fIx | |
| | x, for any "x" not |
| | listed above |
+---------------------------+----------------------------+

You can set the prompt in several ways:

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

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

o Use a command-line option. You can set the --prompt option on the
command line to mysql. For example:

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

o 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:

[mysql]
prompt=(\\u@\\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 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 in Section 4.2.2.2, "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:

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

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

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

MYSQL CLIENT LOGGING
The mysql client can do these types of logging for statements executed
interactively:

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

o On all platforms, if the --syslog option is given, mysql writes the
statements to the system logging facility. On Unix, this is syslog;
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/messages file.

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

o How Logging Occurs

o Controlling the History File

o syslog Logging Characteristics
How Logging Occurs

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

o 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
--batch or --execute option.

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

o mysql logs each nonignored, nonempty statement line individually.

o If a nonignored statement spans multiple lines (not including the
terminating delimiter), mysql concatenates 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, mysql logs the "SELECT", "'Today is'", ",", "CURDATE()",
and ";" lines as it reads them. It also logs the complete statement,
after mapping SELECT\n'Today is'\n,\nCURDATE() to SELECT 'Today is' ,
CURDATE(), plus a delimiter. Thus, these lines appear in logged output:

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

mysql ignores 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:

o ? matches any single character.

o * matches any sequence of zero or more characters.

To specify additional patterns, use the --histignore option or set the
MYSQL_HISTIGNORE environment 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 for UPDATE and DELETE
statements in addition to statements that refer to passwords, invoke
mysql like this:

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

Controlling the History File

The .mysql_history file 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. See Section 6.1.2.1,
"End-User Guidelines for Password Security". Statements in the file are
accessible from the mysql client when the up-arrow key is used to
recall the history. See Disabling Interactive History.

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

o Set the MYSQL_HISTFILE environment 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.

o Create .mysql_history as a symbolic link to /dev/null; this need be
done only once:

ln -s /dev/null $HOME/.mysql_history
syslog Logging Characteristics

If the --syslog option is given, mysql writes interactive statements to
the system logging facility. Message logging has the following
characteristics.

Logging occurs at the "information" level. This corresponds to the
LOG_INFO priority for syslog on Unix/Linux syslog capability and to
EVENTLOG_INFORMATION_TYPE for 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 identifier MysqlClient followed by these
values:

o SYSTEM_USER

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

o MYSQL_USER

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

o CONNECTION_ID:

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

o DB_SERVER

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

o DB

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

o 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.

MYSQL CLIENT 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 from the contents of the MySQL
Reference Manual. The proper operation of this command requires that
the help tables in the mysql database be initialized with help topic
information (see Section 5.1.14, "Server-Side Help Support").

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

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

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 following
topics:
REPAIR TABLE
REPEAT FUNCTION
REPEAT LOOP
REPLACE
REPLACE FUNCTION

EXECUTING SQL STATEMENTS FROM A TEXT FILE
The mysql client typically is used interactively, like this:

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:

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:

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. Previously, it read them and sent them to the server,
resulting in a syntax error. 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.

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

MYSQL CLIENT TIPS
This section provides information about techniques for more effective
use of mysql and about mysql operational behavior.

o Input-Line Editing

o Disabling Interactive History

o Unicode Support on Windows

o Displaying Query Results Vertically

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

o Disabling mysql Auto-Reconnect

o mysql Client Parser Versus Server Parser
Input-Line Editing

mysql supports input-line editing, which enables you to modify the
current input line in place or recall previous input lines. For
example, the left-arrow and right-arrow keys move horizontally within
the current input line, and the up-arrow and down-arrow keys move up
and down through the set of previously entered lines. Backspace
deletes the character before the cursor and typing new characters
enters them at the cursor position. To enter the line, press Enter.

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 build mysql (for example, the libedit or
readline library).

Documentation for the libedit and readline libraries 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: .editrc for libedit and .inputrc for
readline.

For example, in libedit, Control+W deletes everything before the
current cursor position and Control+U deletes the entire line. In
readline, Control+W deletes the word before the cursor and Control+U
deletes everything before the current cursor position. If mysql was
built using libedit, a user who prefers the readline behavior for these
two keys can put the following lines in the .editrc file (creating the
file if necessary):

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

To see the current set of key bindings, temporarily put a line that
says only bind at the end of .editrc. Then mysql shows the bindings
when it starts. Disabling Interactive History

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

On Windows, the history is stored in memory. Alt+F7 deletes 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
with F7 and recalled (by number) with F9. New input lines entered after
you press Alt+F7 repopulate the current history buffer. Clearing the
buffer does not prevent logging to the Windows Event Viewer, if the
--syslog option was used to start mysql. Closing the console window
also clears the current history buffer.

To disable interactive history on Unix, first delete the .mysql_history
file, if it exists (previous entries are recalled otherwise). Then
start mysql with the --histignore="*" option to ignore all new input
lines. To re-enable the recall (and logging) behavior, restart mysql
without the option.

If you prevent the .mysql_history file from being created (see
Controlling the History File) and use --histignore="*" to start the
mysql client, the interactive history recall facility is disabled
fully. Alternatively, if you omit the --histignore option, 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; the mysql client for Windows is able to use these APIs.
The Windows installer creates an item in the MySQL menu named MySQL
command line client - Unicode. This item invokes the mysql client with
properties set to communicate through the console to the MySQL server
using Unicode.

To take advantage of this support manually, run mysql within 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. Execute mysql.exe with the --default-character-set=utf8 (or
utf8mb4) option. This option is necessary because utf16le is one of
the character sets that cannot be used as the client character set.
See the section called "Impermissible Client Character Sets".

With those changes, mysql can 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 run mysql, you can create a shortcut
that invokes mysql.exe. The shortcut should set the console font to
Lucida Console or some other compatible Unicode font, and pass the
--default-character-set=utf8 (or utf8mb4) option to mysql.exe.

Alternatively, create a shortcut that only sets the console font, and
set the character set in the [mysql] group of your my.ini file:

[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 23:29:50
time_zone: +0200
mail_from: Jones
reply: jones@example.com
mail_to: "John Smith" <smith@example.com>
sbj: UTF-8
txt: >>>>> "John" == John Smith writes:
John> Hi. I think this is a good idea. Is anyone familiar
John> with UTF-8 or Unicode? Otherwise, I'll put this on my
John> TODO list and see what happens.
Yes, please do that.
Regards,
Jones
file: inbox-jani-1
hash: 190402944
1 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 an UPDATE or DELETE
statement but forgotten the WHERE clause 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 a LIMIT clause, or both. This helps
prevent accidents. Safe-updates mode also restricts SELECT statements
that produce (or are estimated to produce) very large result sets.

The --safe-updates option causes mysql to execute the following
statement when it connects to the MySQL server, to set the session
values of the sql_safe_updates, sql_select_limit, and max_join_size
system variables:

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

The SET statement affects statement processing as follows:

o Enabling sql_safe_updates causes UPDATE and DELETE statements to
produce an error if they do not 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;

o Setting sql_select_limit to 1,000 causes the server to limit all
SELECT result sets to 1,000 rows unless the statement includes a
LIMIT clause.

o Setting max_join_size to 1,000,000 causes multiple-table SELECT
statements 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-limit and
--max-join-size options when you invoke mysql:

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

It is possible for UPDATE and DELETE statements to produce an error in
safe-updates mode even with a key specified in the WHERE clause, if the
optimizer decides not to use the index on the key column:

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

o If key comparisons require type conversion, the index may not be
used (see Section 8.3.1, "How MySQL Uses Indexes"). Suppose that an
indexed string column c1 is compared to a numeric value using WHERE
c1 = 2222. For such comparisons, the string value is converted to a
number and the operands are compared numerically (see Section 12.3,
"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:

o EXPLAIN with UPDATE and DELETE statements does not produce
safe-updates errors. This enables use of EXPLAIN plus SHOW WARNINGS
to see why an index is not used, which can be helpful in cases such
as when a range_optimizer_max_mem_size violation or type conversion
occurs and the optimizer does not use an index even though a key
column was specified in the WHERE clause.

o 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
the range_optimizer_max_mem_size value was exceeded or type
conversion occurred, either of which can preclude use of an index.

o 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 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.

For more information about auto-reconnect and its effect on state
information when a reconnection occurs, see Automatic Reconnection
Control[5]. mysql Client Parser Versus Server Parser

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

o The server parser treats strings delimited by " characters as
identifiers rather than as plain strings if the ANSI_QUOTES SQL
mode is enabled.

The mysql client parser does not take the ANSI_QUOTES SQL mode into
account. It treats strings delimited by ", ', and ` characters the
same, regardless of whether ANSI_QUOTES is enabled.

o Within /*! ... */ comments, the mysql client parser interprets
short-form mysql commands. The server parser does not interpret
them because these commands have no meaning on the server side.

If it is desirable for mysql not to interpret short-form commands
within comments, a partial workaround is to use the --binary-mode
option, which causes all mysql commands to be disabled except \C
and \d in noninteractive mode (for input piped to mysql or loaded
using the source command).

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

2. C API Basic Data Structures
https://dev.mysql.com/doc/c-api/5.7/en/c-api-data-structures.html

3. Multiple Statement Execution Support
https://dev.mysql.com/doc/c-api/5.7/en/c-api-multiple-queries.html

4. mysql_change_user()
https://dev.mysql.com/doc/c-api/5.7/en/mysql-change-user.html

5. Automatic Reconnection Control
https://dev.mysql.com/doc/c-api/5.7/en/c-api-auto-reconnect.html

SEE ALSO
For more information, please refer to the MySQL Reference Manual, which
may already be installed locally and which is also available online at
http://dev.mysql.com/doc/.

AUTHOR
Oracle Corporation (http://dev.mysql.com/).

MySQL 5.7 09/06/2021 MYSQL(1)

mysql

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