Killing a MySQL User Session

When you login to MySQL, you are given a connection id. In the example below, this is 40:

 

UNIX > mysql -u andrew -p

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 40

Server version: 5.5.19 MySQL Community Server (GPL)

 

Copyright (c) 2000, 2011, 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>

 

root can see this as the id column in the output from show processlist:

 

mysql> select user();

+----------------+

| user()         |

+----------------+

| root@localhost |

+----------------+

1 row in set (0.00 sec)

 

mysql> show processlist;

+----+--------+-----------+------+---------+------+-------+------------------+

| Id | User   | Host      | db   | Command | Time | State | Info             |

+----+--------+-----------+------+---------+------+-------+------------------+

| 40 | andrew | localhost | NULL | Sleep   | 2327 |       | NULL             |

| 41 | root   | localhost | NULL | Query   |    0 | NULL  | show processlist |

+----+--------+-----------+------+---------+------+-------+------------------+

2 rows in set (0.00 sec)

 

mysql>

 

... and root can use it to kill the session:

 

mysql> select user();

+----------------+

| user()         |

+----------------+

| root@localhost |

+----------------+

1 row in set (0.00 sec)

 

mysql> kill 40;

Query OK, 0 rows affected (0.00 sec)

 

mysql> show processlist;

+----+------+-----------+------+---------+------+-------+------------------+

| Id | User | Host      | db   | Command | Time | State | Info             |

+----+------+-----------+------+---------+------+-------+------------------+

| 41 | root | localhost | NULL | Query   |    0 | NULL  | show processlist |

+----+------+-----------+------+---------+------+-------+------------------+

1 row in set (0.00 sec)

 

mysql>

 

When the user accesses his session, he is to told that it has lost its connection. He is then allowed to reconnect without supplying a password and is given a new connection id:

 

mysql> use test;

No connection. Trying to reconnect...

Connection id:    42

Current database: *** NONE ***

 

Database changed

mysql>