Mastering MySQL 4 [Electronic resources] نسخه متنی

SET TRANSACTION

SET [GLOBAL | SESSION] TRANSACTION ISOLATION LEVEL { READ UNCOMMITTED
| READ COMMITTED | REPEATABLE READ | SERIALIZABLE }

Sets the transaction isolation level. By default it will be for the next transaction only, unless the SESSION or GLOBAL keywords are used (which set the level for all transactions on the current connection or for all transactions on all new connections, respectively).