DB Triggers categories by 3 types,
Based on
1. Timing
2. Event
3. Action
Timing Based Triggers
1. Before
2. After
3.Instead of ( only used for complex views)
Event Based Triggers
1. DDL(Create, Alter, Drop)
2. DML(Insert, Delete, Update)
3. DataBase (After Start up, Before Shutdown)
Action Based Triggers
1. Row Level
2. Statement Level
Totally 2*3*2 = 12 Triggers are there,
1. Before Insert Row
2. Before Insert Statement
3. Before Update Row
4. Before Update Statement
5. Before Delete Row
6. Before Delete Statement
7. After Insert Row
8. After Insert Statement
9. After Update Row
10. After Update Statement
11. After Delete Row
12. After Delete Statement
Instead of trigger can be used for perform DML Operations in complex views(Which is created based on more than one table)
Normally we can not use rollback, commit inside the triggers.
But we can use rollback and commit for a sub transactions which is not affect the main transaction.
for ex
CREATE TRIGGER TRIGGER_X
ON TABLE_X
ROW LEVEL
BEGIN
------------------------------
------------------------SOME CODES----------
------------------------------
INSERT INTO TABLE_Y
VALUES( X,Y,Z,);
COMMIT;
------------------------------
------------------------SOME CODES----------
------------------------------
END TRIGGER_X;
