Restrictions on execution of Select triggers
The following types of SELECT statements do not trigger
any actions when they reference a table or column on which an enabled
Select trigger is defined.
- No triggering column is referenced in the Projection list (for example, a column that appears only in the WHERE clause of a SELECT statement does not execute a Select trigger).
- The SELECT statement references a remote table.
- The SELECT statement calls an aggregate function or an OLAP window aggregation function.
- The SELECT statement includes a set operator (UNION, UNION ALL, INTERSECT, MINUS, or EXCEPT)
- The SELECT statement includes the DISTINCT or UNIQUE keyword.
- The UDR expression that contains the SELECT statement is not in the Projection list.
- The SELECT statement appears within an INSERT INTO statement.
- The SELECT statement appears within a scroll cursor.
- The trigger is a cascading Select trigger.
A cascading Select trigger is a trigger whose actions includes an SPL routine that itself has a triggering SELECT statement. The actions of a cascading Select trigger do not execute, however, and the database server does not return an error.