RELEASE_LOCK

Description

This function is used to release a named lock (i.e., a lock named str) previously obtained by the current session using the GET_LOCK() function.

Syntax

RELEASE_LOCK('str')

Description

Parameters

str: The name of the lock to be released. It is a string.

Return Value

• Returns 1: Indicates that the current session holds the lock and it has been successfully released.
• Returns 0: Indicates that the current session does not hold the lock, and the lock has not been released by the current session.
• Returns NULL: Indicates that the lock does not exist, i.e., it was not obtained by the GET_LOCK() function, or it was released earlier.

Examples

Release the lock named my_lock.

SELECT RELEASE_LOCK('my_lock');

The return result is as follows:

+-------------------------+
| RELEASE_LOCK('my_lock') |
+-------------------------+
|                       0 |
+-------------------------+
1 row in set (0.001 sec)

The return value of 0 indicates that the current session does not hold the lock my_lock, and the lock has not been released by the current session.