Statements That Cause an Implicit Commit

The following commands implicitly end a transaction (as if you had done a COMMIT before executing the command):

Command	Command	Command
`ALTER TABLE`	`BEGIN`	`CREATE INDEX`
`DROP DATABASE`	`DROP INDEX`	`DROP TABLE`
`LOAD MASTER DATA`	`LOCK TABLES`	`RENAME TABLE`
`SET AUTOCOMMIT=1`	`START TRANSACTION`	`TRUNCATE`

UNLOCK TABLES also ends a transaction if any tables currently are locked. Prior to MySQL 4.0.13, CREATE TABLE ends a transaction if the binary update log is enabled.

Transactions cannot be nested. This is a consequence of the implicit COMMIT performed for any current transaction when you issue a START TRANSACTION statement or one of its synonyms.