MySQL in a Nutshell, 2nd Edition

Name

RELEASE_LOCK()

Synopsis

RELEASE_LOCK(string)

This function releases a lock created by GET_LOCK(). The name of the lock is given in parentheses. If successful, 1 is returned; if unsuccessful, 0 is returned. If the lock specified does not exist, NULL is returned. Here is an example:

SELECT RELEASE_LOCK('my_lock');

+-------------------------+
| RELEASE_LOCK('my_lock') |
+-------------------------+
|                       1 |
+-------------------------+

As an alternative to using SELECT, you can use the DO statement. In this case, no results are returned, but the lock is released:

DO RELEASE_LOCK('my_lock');