This statement specifies that Oracle will fire this trigger BEFORE the INSERT/UPDATE or DELETE operation is executed.
CREATE [ OR REPLACE ] TRIGGER trigger_name BEFORE INSERT or UPDATE or DELETE ON table_name [ FOR EACH ROW ] DECLARE -- variable declarations BEGIN -- trigger code EXCEPTION WHEN ... -- exception handling END;
OR REPLACE: It is an optional parameter. It is used to re-create the trigger if it already exists. It facilitates you to change the trigger definition without using a DROP TRIGGER statement.
trigger_name: It specifies the name of the trigger that you want to create.
BEFORE INSERT or UPDATE or DELETE: It specifies that the trigger will be fired before the INSERT or UPDATE or DELETE operation is executed.
table_name: It specifies the name of the table on which trigger operation is being performed.
Consider, you have a "suppliers" table with the following parameters.
You can use the following CREATE TRIGGER query to create a BEFORE INSERT or UPDATE or DELETE Trigger:
Here the trigger name is "SUPPLIERS_T1" and it is fired BEFORE the insert or update or delete operation is executed on the table "suppliers".