Tutorial Mysql, Comandos imprescindibles para administrarlo

En este tutorial de Mysql, vamos a ver lo que mínimo que hay que saber para tener unas nociones de administrar una base de datos de forma básica.

Para esto partimos de la base de que tenemos Mysql instalado y arrancado en nuestra maquina.

1 – Como poner la password a root de Mysql

# mysqladmin -u root password NUEVOPASS

2- Cambiar Password Mysql de root:

Si queremos cambiar el password de mysql siendo el antiguo 123456 por  abcdef

# mysqladmin -u root -p 123456 password 'abcdef'

3- Comprobar si Mysql está arrancado:

# mysqladmin -u root -p ping
Enter password:
myqsld is alive

4- Como comprobar que versión de mysql tengo:

# 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

5 – Para saber el estado del servidor Mysql.

# 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

 6 – Comprobar el valor y estado de todas las variables del servidor Mysql.

# 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                            |
+---------------------------------------------------+----------------------------------------------+

7-  Como ver procesos activos de mysql:

# mysqladmin -u root -p processlist

Enter password:
+-------+---------+-----------------+---------+---------+------+-------+------------------+
| Id    | User    | Host            | db      | Command | Time | State | Info             |
+-------+---------+-----------------+---------+---------+------+-------+------------------+
| 18001 | rsyslog | localhost:38307 | rsyslog | Sleep   | 5590 |       |                  |
| 18020 | root    | localhost       |         | Query   | 0    |       | show processlist |
+-------+---------+-----------------+---------+---------+------+-------+------------------+

8 – Crear Base de datos en Mysql:

# 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>

9 – Como quitar una base de datos de mysql:

# 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

10 – Como recargar los privilegios en  Mysql

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

11 – 2 formas de como apagar mysql de forma segura:

mysqladmin -u root -p shutdown

Enter password:

A través del script arranque/parada:

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

12 –  Matar procesos zombis:

# mysqladmin -u root -p processlist

Enter password:
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 5  | root | localhost |    | Sleep   | 14   |       |					 |
| 8  | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

Ahora ejecutamos un kill al ID del  proceso en cuestión:

# mysqladmin -u root -p kill 5

Enter password:
+----+------+-----------+----+---------+------+-------+------------------+
| Id | User | Host      | db | Command | Time | State | Info             |
+----+------+-----------+----+---------+------+-------+------------------+
| 12 | root | localhost |    | Query   | 0    |       | show processlist |
+----+------+-----------+----+---------+------+-------+------------------+

13 – Conectar a un servidor mysql remoto:

# mysqladmin  -h 172.16.25.126 -u root -p

14 – ejecutar comando servidor remoto:

# mysqladmin  -h 172.16.25.126 -u root -p

15 – Arrancar y parar replicación de mysql en un servidor:

# mysqladmin  -u root -p start-slave

# mysqladmin  -u root -p stop-slave

Fuente:  www.tecmint.com