How to create Triggers in SQL

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))  
BEGIN AUTOMIC  
SIGNAL SQLSTATE '75001' ('RAISE EXCEEDS 50%');  
END

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.