Syntax:
    tbl_name [AS alias] {READ [LOCAL] | [LOW_PRIORITY] WRITE}
    [, tbl_name [AS alias] {READ [LOCAL] | [LOW_PRIORITY] WRITE}] ...

If any of the tables are locked by other threads, it blocks until all
locks can be acquired. UNLOCK TABLES releases any locks held by the
current thread. All tables that are locked by the current thread are
implicitly unlocked when the thread issues another LOCK TABLES, or when
the connection to the server is closed.

A table lock protects only against inappropriate reads or writes by
other clients. The client holding the lock, even a read lock, can
perform table-level operations such as DROP TABLE.
