Useful MySQL Commands

Database with size

SELECT table_schema "DB Name",  Round(Sum(data_length + index_length) / 1024 / 1024, 1) "DB Size in MB" FROM   information_schema.tables GROUP  BY table_schema;

Create a database.

mysql> create database [databasename];

List all databases on the server.

mysql> show databases;

Switch to a database.

mysql> use [db name];

To see all the tables in the db.

mysql> show tables;

To see table’s field formats.

mysql> describe [table name];

To delete a db.

mysql> drop database [database name];

To delete a table.

mysql> drop table [table name];

Creating a new user. Login as root. Switch to the MySQL db. Make the user. Update privs.

# mysql -u root -p

mysql> use mysql;
mysql> INSERT INTO user (Host,User,Password) VALUES('%','username',PASSWORD('password'));
mysql> flush privileges;

Change a users password from unix shell.

# [mysql dir]/bin/mysqladmin -u username -h hostname -ppassword 'new-password'

Change a users password from MySQL prompt. Login as root. Set the password. Update privileges.

# mysql -u root -p
mysql> SET PASSWORD FOR 'user'@'hostname' = PASSWORD('password');
mysql> flush privileges;

Recover a MySQL root password. Stop the MySQL server process. Start again with no grant tables. Login to MySQL as root. Set new password. Exit MySQL and restart MySQL server.

# /etc/init.d/mysql stop
# mysqld_safe --skip-grant-tables
# mysql -u root
mysql> use mysql;
mysql> update user set password=PASSWORD("newpassword") where User='root';
mysql> flush privileges;
mysql> quit
# /etc/init.d/mysql stop
# /etc/init.d/mysql start

Set a root password if there is no root password.
# mysqladmin -u root password newpassword

Update a root password.
# mysqladmin -u root -p oldpassword newpassword,

Allow the user “Someone” to connect to the server from localhost using the password “passwd”. Login as root. Switch to the MySQL db. Give privs. Update privs.

# mysql -u root -p
mysql> use mysql;
mysql> grant usage on *.* to Someone@localhost identified by 'passwd';
mysql> flush privileges;

Give user privilages for a db. Login as root. Switch to the MySQL db. Grant privs. Update privs.

mysql> grant all privileges on databasename.* to username@localhost;
mysql> flush privileges;

Dump all databases for backup. Backup file is sql commands to recreate all db’s.

# mysqldump -u username -ppassword --opt > /tmp/alldatabases.sql

Dump one database for backup.

# mysqldump -u username -ppassword --databases databasename > /tmp/databasename.sql

Restore database (or database table) from backup.

# mysql -u username -ppassword databasename < /tmp/databasename.sql

Create Table Example 1.

mysql> CREATE TABLE [table name] (name VARCHAR(20));

Create user/database and grant permission.

CREATE USER 'user'@'localhost' IDENTIFIED BY 'hRAYY3FJjOg';
GRANT ALL ON database.* TO 'user'@'localhost';

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