How is INSTEAD OF trigger different from BEFORE and AFTER triggers?
What will be an ideal response?
The BEFORE and AFTER triggers are based on database tables. Oracle (8i onwards) provides another type of trigger called INSTEAD OF trigger, which is not based on a table but is based on a view. The INSTEAD OF trigger is a row trigger. If a view is based on a SELECT query that contains set operators, group functions, GROUP BY and HAVING clauses, DISTINCT function, join and/or ROWNUM pseudocolumn, data manipulation is not possible through it. An INSTEAD OF trigger is used to modify a table that cannot be modfied through a view. This trigger fires ‘instead of’ triggering DML statements like DELETE, UPDATE or INSERT.
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