Important Facts About MySQL Server

Akshay Phadke
May 04, 2015
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If you have a fresh installation of MySQL server, then it doesn’t require a password to connect as the root user. To set the MySQL password for the root user, use the following command.

# mysqladmin -u root password YOURNEWPASSWORD

How to Change MySQL Root password

If you would like to change or update the MySQL root password, then you need to use the following command. For example, say your old password is 123456 and you want to change it to a new password, say xyz123. Use the following:

mysqladmin -u root -p123456 password 'xyz123'.

How to determine if MySQL Server is running

To determine whether the MySQL server is up and running, use the following command.

# mysqladmin -u root -p ping

Enter password:

mysqld is alive

How to determine which MySQL version I am running

The following command shows the MySQL version along with the current running status.

# mysqladmin -u root -p version

Enter password:

mysqladmin Ver 8.42 Distrib 5.5.28, for Linux on i686
Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Server version	5.5.28
Protocol version	10
Connection	Localhost via UNIX socket
UNIX socket	/var/lib/mysql/mysql.sock
Uptime:	7 days 14 min 45 sec

Threads: 2 Questions: 36002 Slow queries: 0 Opens: 15 Flush tables: 1 Open tables: 8 Queries per second avg: 0.059

How to determine current Status of MySQL server

To determine the current status of the MySQL server, use the following command. The mysqladmin command shows the status of uptime with the running threads and queries.

# mysqladmin -u root -ptmppassword status

Enter password:

Uptime: 606704 Threads: 2 Questions: 36003 Slow queries: 0 Opens: 15 Flush tables: 1 Open tables: 8 Queries per second avg: 0.059

How to determine the status of all MySQL Server Variables and values

To check all the running status of MySQL server variables and values, type the following command. The output would be similar to below.

# mysqladmin -u root -p extended-status

Enter password:

Variable_name	Value
Aborted_clients	3
Aborted_connects	3
Binlog_cache_disk_use	0
Binlog_cache_use	0
Binlog_stmt_cache_disk_use	0
Binlog_stmt_cache_use	0
Bytes_received	6400357
Bytes_sent	2610105
Com_admin_commands	3
Com_assign_to_keycache	0
Com_alter_db	0
Com_alter_db_upgrade	0
Com_alter_event	0
Com_alter_function	0
Com_alter_procedure	0
Com_alter_server	0
Com_alter_table	0
Com_alter_tablespace	0

How to see all MySQL server Variables and Values

To see all the running variables and values of MySQL server, use the following command.

# mysqladmin -u root -p variables

Enter password:

Variable_name	Value
auto_increment_increment	1
auto_increment_offset	1
autocommit	ON
automatic_sp_privileges	ON
back_log	50
basedir	/usr
big_tables	OFF
binlog_cache_size	32768
binlog_direct_non_transactional_updates	OFF
binlog_format	STATEMENT
binlog_stmt_cache_size	32768
bulk_insert_buffer_size	8388608
character_set_client	latin1
character_set_connection	latin1
character_set_database	latin1
character_set_filesystem	binary
character_set_results	latin1
character_set_server	latin1
character_set_system	utf8
character_sets_dir /usr/share/mysql/charsets/
collation_connection	latin1_swedish_ci

How to check all the running Process of MySQL server

The following command will display all the running process of MySQL database queries.

# mysqladmin -u root -p processlist

Enter password:

Id Info	User	Host	db	Command	Time	State
18001	rsyslog	localhost:38307	rsyslog	Sleep	5590
18020	root	localhost		Query	0
Show process List

How to create a Database in MySQL server

To create a new database in MySQL server, use the command as shown below.

# mysqladmin -u root -p create databasename

Enter password:

# mysql -u root -p

Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 18027
Server version: 5.5.28 MySQL Community Server (GPL) by Remi

Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

Database

information_schema

databasename

mysql

test

8 rows in set (0.01 sec)

mysql>

How to drop a database in MySQL server

To drop a database in MySQL server, use the following command. You will be asked to confirm by pressing ‘y‘.

# mysqladmin -u root -p drop databasename

Enter password:

Dropping the database is potentially a very bad thing to do.
Any data stored in the database will be destroyed.

Do you really want to drop the 'databasename' database [y/N] y
Database "databasename" dropped.

How to reload/refresh MySQL Privileges

The reload command tells the server to reload the grant tables. The refresh command flushes all tables and reopens the log files.

# mysqladmin -u root -p reload;
# mysqladmin -u root -p refresh

How to shutdown MySQL server Safely

To shutdown MySQL server safely, type the following command.

mysqladmin -u root -p shutdown

Enter password:

You can also use the following commands to start/stop MySQL server.

# /etc/init.d/mysqld stop
# /etc/init.d/mysqld start

Some useful MySQL Flush commands

The following are some useful flush commands with their description.

flush-hosts: Flush all host information from host cache.
flush-tables: Flush all tables.
flush-threads: Flush all threads cache.
flush-logs: Flush all information logs.
flush-privileges: Reload the grant tables (same as reload).
flush-status: Clear status variables.

# mysqladmin -u root -p flush-hosts
# mysqladmin -u root -p flush-tables
# mysqladmin -u root -p flush-threads
# mysqladmin -u root -p flush-logs
# mysqladmin -u root -p flush-privileges
# mysqladmin -u root -p flush-status

How to kill Sleeping MySQL Client Process

Use the following command to identify a sleeping MySQL client process.

# mysqladmin -u root -p processlist

Enter password:

Id	User	Host	db	Command	Time	States	Info
5	root	localhost		sleep	14		show processlist
8	root	localhost		Query	0

Now, run the following command with kill and process ID as shown below.

# mysqladmin -u root -p kill 5

Enter password:

Id	User	Host	db	Command	Time	States	Info
12	root	localhost		Query	0		show processlist

If you like to kill multiple processes then pass the process IDs separated by commas as shown below.

# mysqladmin -u root -p kill 5,10

How to run multiple mysqladmin commands together

If you would like to execute multiple ‘mysqladmin‘ commands together, then the command would be like this.

# mysqladmin -u root -p processlist status version

Enter password:

Id	User	Host	db	Command	Time	States	Info
8	root	localhost		Query	0		show processlist

Uptime: 3801 Threads: 1 Questions: 15 Slow queries: 0 Opens: 15 Flush tables: 1 Open tables: 8 Queries per second avg: 0.003

mysqladmin Ver 8.42 Distrib 5.5.28, for Linux on i686

Copyright (c) 2000, 2012, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its affiliates. Other names may be trademarks of their respective owners.

Server version	5.5.28
Protocol version	10
Connection	Localhost via UNIX socket
UNIX socket	/var/lib/mysql/mysql.sock
Uptime:	1 hour 3 min 21 sec

Threads: 1 Questions: 15 Slow queries: 0 Opens: 15 Flush tables: 1 Open tables: 8 Queries per second avg: 0.003

16. How to connect to remote MySQL server

To connect to a remote MySQL server, use the -h (host) with IP Address of remote machine.

# mysqladmin -h 172.16.25.126 -u root -p

How to execute command on remote MySQL server

Let’s say you would like to see the status of a remote MySQL server, then the command would be:

# mysqladmin -h 172.16.25.126 -u root -p status

How to start/stop MySQL replication on a slave server

To start/stop MySQL replication on the same server, use the following commands.

# mysqladmin -u root -p start-slave
# mysqladmin -u root -p stop-slave

How to store MySQL server Debug Information to logs

It tells the server to write debug information about locks in use, used memory and query usage to the MySQL log file including information about the event scheduler.

# mysqladmin -u root -p debug

Enter password:

How to view mysqladmin options and usage

To determine more options and usage of the myslqadmin command use the help command as shown below. It will display a list of available options.

# mysqladmin --help

We have tried our best to include almost all of the ‘mysqladmin‘ commands with their examples in this article, still, if we’ve missed anything, please do let us know via comments and don’t forget to share with your friends.

Using the mysqldump Command

The mysqldump command creates a text version of the database. Specifically, it creates a list of SQL statements that can be used to restore/recreate the original database.

The syntax is:

$ mysqldump -u [uname] -p[pass] [dbname] > [backupfile.sql]

[uname] Your database username

[pass] The password for your database

[dbname] The name of your database

[backupfile.sql] The filename for your database backup

You can dump a table, a database, or all databases.

To dump all MySQL databases on the system, use the --all-databases shortcut: