You can specify when triggers fire.
| WHEN you specify… | THEN the triggered action… |
|---|---|
| BEFORE | executes before the completion of the triggering event. As specified in the ANSI/ISO SQL standard, a BEFORE trigger cannot have data changing statements in the triggered action. |
| AFTER | executes after completion of the triggering event. To support stored procedures the CALL statement is supported in the body of an AFTER trigger. Both row and statement triggers can call a stored procedure.
|
Sometimes a request fires a trigger, which in turn, fires another trigger. Thus the outcome of one triggering event can itself become another trigger. Teradata Database processes and optimizes the triggered and triggering statements in parallel to maximize system performance.