Sams Teach Yourself SQL in 21 Days, Fourth Edition

Designing and Using Triggers

A trigger is essentially a special type of stored procedure that can be executed in response to one of three conditions:

• UPDATE

• INSERT

• DELETE

The Transact-SQL syntax to create a trigger looks like this:

CREATE TRIGGER TRIGGER_NAME
   ON TABLE_NAME
   FOR {INSERT, UPDATE, DELETE}
   AS SQL_STATEMENTS

The Oracle SQL syntax used to create a trigger follows:

 CREATE [OR REPLACE] TRIGGER [SCHEMA.]TRIGGER_NAME {BEFORE | AFTER | INSTEAD OF} {DELETE | INSERT | UPDATE [OF COLUMN[, COLUMN]...]} [OR {DELETE | INSERT | UPDATE [OF COLUMN ...