MySQL in a Nutshell, 2nd Edition

Name

ROLLBACK

Synopsis

ROLLBACK [WORK] [AND [NO] CHAIN] [[NO] RELEASE]

Use this statement with transactional tables to reverse transactions that have not yet been committed. Transaction statements are currently supported by the InnoDB, NDB Cluster, and BDB storage engines and are ignored if used with MyISAM tables.

If AUTOCOMMIT is enabled, it must be disabled for this statement to be meaningful, which can be done as follows:

SET AUTOCOMMIT = 0;

AUTOCOMMIT is also disabled when a transaction is started with the START TRANSACTION statement. It is reinstated with the execution of the COMMIT statement, the ending of the current session, and several other statements that imply that a commit is desired. See the explanation of COMMIT earlier in this chapter for a list of statements that imply a commit.

The WORK keyword is optional and has no effect on the results. It’s available for compatibility with its counterparts, BEGIN WORK and COMMIT WORK. Use the AND CHAIN clause to indicate that the transaction is to be rolled back and another is starting, thus making it unnecessary to execute the START TRANSACTION statement again. Use the AND RELEASE clause to end the current client session after rolling back the transaction. Add the keyword NO to indicate explicitly that a new transaction is not to begin (when used with CHAIN) or the client session is not to end (when used with RELEASE)—these are the default settings, though. It’s necessary to specify NO only when the system variable completion_type ...