Provided by: drizzle-client_7.2.3-2ubuntu2_amd64 
DRIZZLE(1) Drizzle Database System DRIZZLE(1)
NAME
drizzle - the Drizzle command-line tool
SYNOPSIS
drizzle [options] db_name
DESCRIPTION
drizzle 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 drizzle 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.
Using drizzle is very easy. Invoke it from the prompt of your command interpreter as
follows:
shell> drizzle db_name
Or:
shell> drizzle --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 drizzle to attempt to kill the current statement. If this cannot
be done, or Control-C is typed again before the statement is killed, drizzle exits.
You can execute SQL statements in a script file (batch file) like this:
shell> drizzle db_name < script.sql > output.tab
DRIZZLE OPTIONS
drizzle supports the options in the following list.
• --help, -?
Display a help message and exit.
• --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 drizzle to start faster, but you must issue the rehash command if you want to
use name completion.
To complete a name, enter the first part and press Tab. If the name is unambiguous,
drizzle 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.
• --auto-vertical-output
Causes 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.) This option was added in Drizzle 6.0.4.
• --batch, -B
Print results using tab as the column separator, with each row on a new line. With this
option, drizzle does not use the history file.
Batch mode results in non-tabular output format and escaping of special characters.
Escaping may be disabled by using raw mode; see the description for the --raw option.
• --character-sets-dir=path
The directory where character sets are installed. See Section 9.2, “The Character Set
Used for Data and Sorting”.
• --column-names
Write column names in results.
• --column-type-info, -m
Display result set metadata.
• --comments, -c
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 Drizzle 6.0.4.
• --compress, -C
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-check
Print some debugging information when the program exits.
• --debug-info, -T
Print debugging information and memory and CPU usage statistics when the program exits.
• --delimiter=str
Set the statement delimiter. The default is the semicolon character (“;”).
• --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 (“;”). drizzle 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 COMMANDS”.
• --execute=statement, -e statement
Execute the statement and quit. The default output format is like that produced with
--batch. See Section 4.2.3.1, “Using Options on the Command Line”, for some examples.
• --force, -f
Continue even if an SQL error occurs.
• --host=host_name, -h host_name
Connect to the Drizzle server on the given host.
• --html, -H
Produce HTML output.
• --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 5.1.7, “Server SQL Modes”).
• --line-numbers
Write line numbers for errors. Disable this with --skip-line-numbers.
• --local-infile[={0|1}]
Enable or disable LOCAL capability for LOAD DATA INFILE. With no value, the option
enables LOCAL. The option may be given as --local-infile=0 or --local-infile=1 to
explicitly disable or enable LOCAL. Enabling LOCAL has no effect if the server does not
also support it.
• --named-commands, -G
Enable named drizzle commands. Long-format commands are allowed, 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 COMMANDS”.
• --no-auto-rehash, -A
Deprecated form of -skip-auto-rehash. Use --disable-auto-rehash instead. See the
description for --auto-rehash.
• --no-beep, -b
Do not beep when errors occur.
• --no-named-commands, -g
Deprecated, use --disable-named-commands instead.
• --no-pager
Deprecated form of --skip-pager. See the --pager option.
• --no-tee
Do not copy output to a file. the section called “MYSQL COMMANDS”, discusses tee files
further.
• --one-database, -o
Ignore statements except those for the default database named on the command line. This
is useful for skipping updates to other databases in the binary log.
• --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. It does not work in batch
mode. To disable paging, use --skip-pager. the section called “MYSQL COMMANDS”,
discusses output paging further.
• --password[=password], -P[password]
The password to use when connecting to the server. If you use the short option form
(-p), you cannot have a space between the option and the password. If you omit the
password value following the --password or -p option on the command line, you are
prompted for one.
Specifying a password on the command line should be considered insecure. See
Section 5.5.6.2, “End-User Guidelines for Password Security”.
• --pipe, -W
On Windows, connect to the server via a named pipe. This option applies only for
connections to a local server, and only if the server supports named-pipe connections.
• --port=port_num, -p port_num
The TCP/IP port number to use for the connection.
• --prompt=format_str
Set the prompt to the specified format. The default is drizzle>. The special sequences
that the prompt can contain are described in the section called “MYSQL COMMANDS”.
• --protocol={TCP|SOCKET|PIPE|MEMORY}
The connection protocol to use for connecting to the server. It is useful when the
other connection parameters normally would cause a protocol to be used other than the
one you want. For details on the allowable values, see Section 4.2.2, “Connecting to
the Drizzle Server”.
• --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, drizzle does not use the
history file.
• --raw, -r
For tabular output, the “boxing” around columns enables one column value to be
distinguished from another. For non-tabular 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 non-tabular output and the use of raw
mode to disable escaping:
% drizzle
drizzle> SELECT CHAR(92);
+----------+
| CHAR(92) |
+----------+
| \ |
+----------+
% drizzle -s
drizzle> SELECT CHAR(92);
CHAR(92)
\\
% drizzle -s -r
drizzle> SELECT CHAR(92);
CHAR(92)
\
• --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.
• --safe-updates, --i-am-a-dummy, -U
Allow only those UPDATE and DELETE statements 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-updates on the command line. See the section called “MYSQL TIPS”, for more
information about this option.
• --secure-auth
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.
• --show-warnings
Cause warnings to be shown after each statement if there are any. This option applies
to interactive and batch mode.
• --sigint-ignore
Ignore SIGINT signals (typically the result of typing Control-C).
• --silent, -s
Silent mode. Produce less output. This option can be given multiple times to produce
less and less output.
This option results in non-tabular output format and escaping of special characters.
Escaping may be disabled by using raw mode; see the description for the --raw option.
• --skip-column-names, -N
Do not write column names in results. The short format, -N is deprecated, use the long
format instead.
• --skip-line-numbers, -L
Do not write line numbers for errors. Useful when you want to compare result files that
include error messages. The short format, -L is deprecated, use the long format
instead.
• --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.
• --ssl*
Options that begin with --ssl specify whether to connect to the server via SSL and
indicate where to find SSL keys and certificates. See Section 5.5.7.3, “SSL Command
Options”.
• --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.
• --tee=file_name
Append a copy of output to the given file. This option does not work in batch mode.
the section called “MYSQL COMMANDS”, discusses tee files further.
• --unbuffered, -n
Flush the buffer after each query.
• --user=user_name, -u user_name
The Drizzle user name to use when connecting to the server.
• --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.)
• --version, -V
Display version information and exit.
• --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.
• --wait, -w
If the connection cannot be established, wait and retry instead of aborting.
You can also set the following variables by using
--var_name=value. The --set-variable format is deprecated.
• connect_timeout
The number of seconds before connection timeout. (Default value is 0.)
• max_allowed_packet
The maximum packet length to send to or receive from the server. (Default value is
16MB.)
• max_join_size
The automatic limit for rows in a join when using --safe-updates. (Default value is
1,000,000.)
• net_buffer_length
The buffer size for TCP/IP and socket communication. (Default value is 16KB.)
• select_limit
The automatic limit for SELECT statements when using --safe-updates. (Default value is
1,000.)
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. See Section 5.5.6.2, “End-User Guidelines for Password Security”.
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:
• Set the MYSQL_HISTFILE variable 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_history as a symbolic link to /dev/null:
shell> ln -s /dev/null $HOME/.mysql_history
You need do this only once.
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 Drizzle 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.
• help [arg], \h [arg], \? [arg], ? [arg]
Displays 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 Drizzle Reference Manual. For more
information, see the section called “MYSQL SERVER-SIDE HELP”.
• charset charset_name, \C charset_name
The charset command changes the default character set and issues 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.
• clear, \c
Clears 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]]
Reconnects 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
The delimiter command changes the string that mysql interprets as the separator between
SQL statements. The default is the semicolon character (“;”).
The delimiter can be specified as an unquoted or quoted argument. Quoting can be done
with either single quote (') or douple quote (") characters. To include a quote within
a quoted string, either quote the string with the other 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 Drizzle. For an unquoted argument, the
delmiter 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.
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 Section 20.10.12, “C API Support for Multiple
Statement Execution”), and for parsing the body of stored procedures and functions,
triggers, and events (see Section 18.1, “Defining Stored Programs”).
• edit, \e
Edits 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.
• ego, \G
Sends the current statement to the server to be executed and displays the result using
vertical format.
• exit, \q
Exits mysql.
• go, \g
Sends the current statement to the server to be executed.
• nopager, \n
Disables output paging. See the description for pager.
The nopager command works only in Unix.
• notee, \t
Disables output copying to the tee file. See the description for tee.
• nowarning, \w
Enables display of warnings after each statement.
• pager [command], \P [command]
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.
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.
• print, \p
Prints the current input statement without executing it.
• prompt [str], \R [str]
Reconfigures 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>.
• quit, \q
Exits mysql.
• rehash, \#
Rebuilds the completion hash that enables database, table, and column name completion
while you are entering statements. (See the description for the --auto-rehash option.)
• source file_name, \. file_name
Reads the named file and executes the statements contained therein. On Windows, you can
specify path name separators as / or \\.
• status, \s
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.
• system command, \! command
Executes the given command using your default command interpreter.
The system command works only in Unix.
• 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.
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.
• use db_name, \u db_name
Uses db_name as the default database.
• warnings, \W
Enables display of warnings after each statement (if there are any).
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
• 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
• 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 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 prompt command reconfigures the default drizzle> prompt. The string for defining the
prompt can contain the following special sequences.
┌───────────────────────────────┬────────────────────────────────┐
│Option │ Description │
├───────────────────────────────┼────────────────────────────────┤
│\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@host │
│ │ account name │
├───────────────────────────────┼────────────────────────────────┤
│\u │ Your user name │
├───────────────────────────────┼────────────────────────────────┤
│\c │ A counter that increments for │
│ │ each statement you issue │
├───────────────────────────────┼────────────────────────────────┤
│\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 │
├───────────────────────────────┼────────────────────────────────┤
│\T}:T{ A literal “\” backslash │ │
│character │ │
├───────────────────────────────┼────────────────────────────────┤
│\x │ x, for any │
│ │ “x” not listed │
│ │ above │
├───────────────────────────────┼────────────────────────────────┤
│\D │ The full current date │
├───────────────────────────────┼────────────────────────────────┤
│\d │ The default database │
├───────────────────────────────┼────────────────────────────────┤
│\h │ The server host │
├───────────────────────────────┼────────────────────────────────┤
│\l │ The current delimiter │
├───────────────────────────────┼────────────────────────────────┤
│\m │ Minutes of the current time │
├───────────────────────────────┼────────────────────────────────┤
│\n │ A newline character │
├───────────────────────────────┼────────────────────────────────┤
│\O │ The current month in │
│ │ three-letter format (Jan, Feb, │
│ │ ...) │
└───────────────────────────────┴────────────────────────────────┘
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="(\u@\h) [\d]> "
• 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]>
• Use an option file. You can set the prompt option in the [mysql] group of any Drizzle
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 allowable prompt options and
the set of special escape sequences that are recognized in option files. (These sequences
are listed in Section 4.2.3.2, “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:
[mysql]
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 (\u@\h) [\d]>\_
PROMPT set to '(\u@\h) [\d]>\_'
(user@host) [database]>
(user@host) [database]> prompt
Returning to default PROMPT of mysql>
mysql>
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 from the contents of the Drizzle 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 5.1.8, “Server-Side Help”).
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>.
As of Drizzle 6.0.4, 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 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 Drizzle server:
SET sql_safe_updates=1, sql_select_limit=1000, sql_max_join_size=1000000;
See Section 5.1.4, “Session System Variables”.
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: Drizzle 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 Section 20.10.11, “Controlling Automatic Reconnection Behavior”.
COPYRIGHT
Copyright 2007-2008 MySQL AB, 2009 Sun Microsystems, Inc.
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/.
REFERENCES
1. Bug#25946
http://bugs.mysql.com/25946
SEE ALSO
For more information, please refer to the Drizzle Reference Manual, which may already be
installed locally and which is also available online at http://dev.mysql.com/doc/.
AUTHOR
Sun Microsystems, Inc. (http://www.mysql.com/).
Drizzle 05/23/2009 DRIZZLE(1)