MySQL in a Nutshell, 2nd Edition

Name

UNLOCK TABLES

Synopsis

UNLOCK TABLES

Use this statement to unlock tables that were locked by the current connection thread with the LOCK TABLES statement or by FLUSH TABLES WITH READ LOCK. UNLOCK TABLES implicitly commits any active transactions if any tables were locked with LOCK TABLES. When performing a large amount of changes to data in MyISAM tables, it can be useful and faster to lock the tables first. This way the key cache isn’t flushed after each SQL statement. Instead, the server flushes the key cache when executing UNLOCK TABLES. Here is an example:

UNLOCK TABLES;