How to write Triggers?
The following code shows the creation in DB2:
CREATE TRIGGER SALARY_UPDATE
BEFORE UPDATE OF SALARAY ON EMP_TABLE
FOR EACH ROW MODE DB2SQL
WHEN (NEW.SALARY > (OLD.SALARY * 1.5))
SIGNAL SQLSTATE '75001' ('RAISE EXCEEDS 50%');
SALARY_UPDATE: Trigger Name
The trigger will fire before actual update. It applies to all update rows. Begin and End are the actual Trigger statements.
New value exceeds 50% of old salary. An error will raise. Triggers will be stored in Trigger package. Trigger packages also stored in SYSPACKAGE.