ROLLBACK [ WORK | TRANSACTION ]
ROLLBACK rolls back the current transaction and causes all the updates made by the transaction to be discarded.
Use COMMIT [commit(7)] to successfully terminate a transaction.
Issuing ROLLBACK when not inside a transaction does no harm, but it will provoke a warning message.
To abort all changes:
The SQL standard only specifies the two forms ROLLBACK and ROLLBACK WORK. Otherwise, this command is fully conforming.