Transactions and exceptions v15
A trigger is always executed as part of the same transaction in which the triggering statement is executing. When no exceptions occur in the trigger code block, the effects of any triggering commands in the trigger are committed only if the transaction containing the triggering statement is committed. Therefore, if the transaction is rolled back, the effects of any triggering commands in the trigger are also rolled back.
If an exception does occur in the trigger code block, but it is caught and handled in an exception section, the effects of any triggering commands in the trigger are still rolled back. The triggering statement, however, is rolled back only if the application forces a rollback of the containing transaction.
If an unhandled exception occurs in the trigger code block, the transaction that contains the trigger is aborted and rolled back. Therefore, the effects of any triggering commands in the trigger and the triggering statement are all rolled back.