difference before and after trigger in oracle

Question

Can somebody explain difference between \"before\" and \"after\" trigger in oracle 10g with an example ?

Answer 1

BEFORE TRIGGER are used when the trigger action should determine whether or not the triggering statements should be allowed to complete .by using BEFORE TRIGGERS user can eliminate unnecessary processing of the triggering statement but,AFTER TRIGGERS are used when the triggering statements should completed before executing the trigger action.