Sunday, May 10, 2009

Connecting to and disconnecting from MySQL

With the MySQL server installed and MySQL server daemon (Unix) or MySQL service (Windows) running you can connect to mysql database.

In order to know a list of mysql commands on your console, go to mysql installation directory and then into bin folder. Writing mysql --help you provide of a list of commands which you can use with mysql command. Output is shown below.

D:\xampp\mysql\bin>mysql --help
mysql  Ver 14.14 Distrib 5.1.30, for Win32 (ia32)
Copyright 2000-2008 MySQL AB, 2008 Sun Microsystems, Inc.
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL license
Usage: mysql [OPTIONS] [database]
-?, --help Display this help and exit.
-I, --help Synonym for -?
--auto-rehash Enable automatic rehashing. One doesn't need to use
'rehash' to get table and field completion, but startup
and reconnecting may take a longer time. Disable with
--disable-auto-rehash.
-A, --no-auto-rehash
No automatic rehashing. One has to use 'rehash' to get
table and field completion. This gives a quicker start of
mysql and disables rehashing on reconnect. WARNING:
options deprecated; use --disable-auto-rehash instead.
-B, --batch Don't use history file. Disable interactive behavior.
(Enables --silent)
--character-sets-dir=name
Directory where character sets are.
--column-type-info Display column type information.
-c, --comments Preserve comments. Send comments to the server. The
default is --skip-comments (discard comments), enable
with --comments
-C, --compress Use compression in server/client protocol.
-#, --debug[=#] This is a non-debug version. Catch this and exit
--debug-check Check memory and open file usage at exit .
-T, --debug-info Print some debug info at exit.
-D, --database=name Database to use.
--default-character-set=name
Set the default character set.
--delimiter=name Delimiter to be used.
-e, --execute=name Execute command and quit. (Disables --force and history
file)
-E, --vertical Print the output of a query (rows) vertically.
-f, --force Continue even if we get an sql error.
-G, --named-commands
Enable named commands. Named commands mean this program's
internal commands; see mysql> help . When enabled, the
named commands can be used from any line of the query,
otherwise only from the first line, before an enter.
Disable with --disable-named-commands. This option is
disabled by default.
-g, --no-named-commands
Named commands are disabled. Use \* form only, or use
named commands only in the beginning of a line ending
with a semicolon (;) Since version 10.9 the client now
starts with this option ENABLED by default! Disable with
'-G'. Long format commands still work from the first
line. WARNING: option deprecated; use
--disable-named-commands instead.
-i, --ignore-spaces Ignore space after function names.
--local-infile Enable/disable LOAD DATA LOCAL INFILE.
-b, --no-beep Turn off beep on error.
-h, --host=name Connect to host.
-H, --html Produce HTML output.
-X, --xml Produce XML output
--line-numbers Write line numbers for errors.
-L, --skip-line-numbers
Don't write line number for errors. WARNING: -L is
deprecated, use long version of this option instead.
-n, --unbuffered Flush buffer after each query.
--column-names Write column names in results.
-N, --skip-column-names
Don't write column names in results. WARNING: -N is
deprecated, use long version of this options instead.
-O, --set-variable=name
Change the value of a variable. Please note that this
option is deprecated; you can set variables directly with
--variable-name=value.
--sigint-ignore Ignore SIGINT (CTRL-C)
-o, --one-database Only update the default database. This is useful for
skipping updates to other database in the update log.
-p, --password[=name]
Password to use when connecting to server. If password is
not given it's asked from the tty.
-W, --pipe Use named pipes to connect to server.
-P, --port=# Port number to use for connection or 0 for default to, in
order of preference, my.cnf, $MYSQL_TCP_PORT,
/etc/services, built-in default (3306).
--prompt=name Set the mysql prompt to this value.
--protocol=name The protocol of connection (tcp,socket,pipe,memory).
-q, --quick Don't cache result, print it row by row. This may slow
down the server if the output is suspended. Doesn't use
history file.
-r, --raw Write fields without conversion. Used with --batch.
--reconnect Reconnect if the connection is lost. Disable with
--disable-reconnect. This option is enabled by default.
-s, --silent Be more silent. Print results with a tab as separator,
each row on new line.
--shared-memory-base-name=name
Base name of shared memory.
-S, --socket=name Socket file to use for connection.
--ssl Enable SSL for connection (automatically enabled with
other flags). Disable with --skip-ssl.
--ssl-ca=name CA file in PEM format (check OpenSSL docs, implies
--ssl).
--ssl-capath=name CA directory (check OpenSSL docs, implies --ssl).
--ssl-cert=name X509 cert in PEM format (implies --ssl).
--ssl-cipher=name SSL cipher to use (implies --ssl).
--ssl-key=name X509 key in PEM format (implies --ssl).
--ssl-verify-server-cert
Verify server's "Common Name" in its cert against
hostname used when connecting. This option is disabled by
default.
-t, --table Output in table format.
--tee=name Append everything into outfile. See interactive help (\h)
also. Does not work in batch mode. Disable with
--disable-tee. This option is disabled by default.
--no-tee Disable outfile. See interactive help (\h) also. WARNING:
option deprecated; use --disable-tee instead
-u, --user=name User for login if not current user.
-U, --safe-updates Only allow UPDATE and DELETE that uses keys.
-U, --i-am-a-dummy Synonym for option --safe-updates, -U.
-v, --verbose Write more. (-v -v -v gives the table output format).
-V, --version Output version information and exit.
-w, --wait Wait and retry if connection is down.
--connect_timeout=# Number of seconds before connection timeout.
--max_allowed_packet=#
Max packet length to send to, or receive from server
--net_buffer_length=#
Buffer for TCP/IP and socket communication
--select_limit=# Automatic limit for SELECT when using --safe-updates
--max_join_size=# Automatic limit for rows in a join when using
--safe-updates
--secure-auth Refuse client connecting to server if it uses old
(pre-4.1.1) protocol
--server-arg=name Send embedded server this as a parameter.
--show-warnings Show warnings after every statement.

Default options are read from the following files in the given order:
E:\WINDOWS\my.ini E:\WINDOWS\my.cnf C:\my.ini C:\my.cnf D:\xampp\mysql\my.ini D:\xampp\mysql\my.cnf
The following groups are read: mysql client
The following options may be given as the first argument:
--print-defaults Print the program argument list and exit
--no-defaults Don't read default options from any options file
--defaults-file=# Only read default options from the given file #
--defaults-extra-file=# Read this file after the global files are read

Variables (--variable-name=value)
and boolean options {FALSE|TRUE} Value (after reading options)
--------------------------------- -----------------------------
auto-rehash TRUE
character-sets-dir (No default value)
column-type-info FALSE
comments FALSE
compress FALSE
debug-check FALSE
debug-info FALSE
database (No default value)
default-character-set latin1
delimiter ;
vertical FALSE
force FALSE
named-commands FALSE
local-infile FALSE
no-beep FALSE
host (No default value)
html FALSE
xml FALSE
line-numbers TRUE
unbuffered FALSE
column-names TRUE
sigint-ignore FALSE
port 0
prompt mysql>
quick FALSE
raw FALSE
reconnect TRUE
shared-memory-base-name (No default value)
socket (No default value)
ssl FALSE
ssl-ca (No default value)
ssl-capath (No default value)
ssl-cert (No default value)
ssl-cipher (No default value)
ssl-key (No default value)
ssl-verify-server-cert FALSE
table FALSE
user (No default value)
safe-updates FALSE
i-am-a-dummy FALSE
connect_timeout 0
max_allowed_packet 16777216
net_buffer_length 16384
select_limit 1000
max_join_size 1000000
secure-auth FALSE
show-warnings FALSE

Note that if the MySQL server daemon (Unix) or service (Windows) is not running, then you would get the error below.

# mysql
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)

If daemon or service is running then to connect into mysql database into host localhost as user root issue,
D:\xampp\mysql\bin>mysql -h localhost -u root -p
Enter password: ****
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.1.30-community MySQL Community Server (GPL)

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>

If you see mysql> prompt as above you are connected to mysql database. And now you can query as you wish. Note that also from shell prompt or console you can query from mysql database.

For example to know the list of mysql database issue,
D:\xampp\mysql\bin>mysql -h localhost -u root -ptest -e "show databases;"
+--------------------+
| Database |
+--------------------+
| information_schema |
| arju |
| email_master_list |
| magento |
| mysql |
| phpmyadmin |
| test |
| webauth |
+--------------------+

Sometimes you can want to remove the column heading. Then use as,

D:\xampp\mysql\bin>mysql -h localhost -u root -ptest -sN -e "show databases;"
information_schema
arju
email_master_list
magento
mysql
phpmyadmin
test
webauth

In order to disconnect from mysql prompt issue exit. Bye will be printed on the screen and it will go to console prompt.
mysql> exit
Bye

D:\xampp\mysql\bin>

On windows you can also exit by pressing CTRL+C in mysql prompt.
On unix press CTRL+D .

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