Pl sql if inserting updating
Unlike a subprogram, a trigger cannot be invoked directly.
A trigger is invoked only by its triggering event, which can be caused by any user or application.
A trigger can have the same name as another kind of object in the schema (for example, a table); however, Oracle recommends using a naming convention that avoids confusion. By default, a trigger is created in the enabled state.
You can disable an enabled trigger, and enable a disabled trigger.
NEXTVAL INTO : NEW.my_col3 FROM DUAL; END IF; IF : NEW.my_col4 IS NULL THEN (...) END IF; END IF; END; / -- Scenario 2 CREATE OR REPLACE TRIGGER my_trg1 BEFORE INSERT ON my_table FOR EACH ROW BEGIN IF : NEW.my_col3 IS NULL THEN SELECT my_seq.
NEXTVAL INTO : NEW.my_col3 FROM DUAL; END IF; IF : NEW.my_col4 IS NULL THEN (...) END IF; END; / CREATE OR REPLACE TRIGGER my_trg2 BEFORE UPDATE ON my_table FOR EACH ROW BEGIN IF : NEW.my_col IS NULL THEN raise_application_error(...); END IF; IF : NEW.my_col2 IS NULL THEN : NEW.my_col2 := (...); END IF; END; / I can't see any major advantage to one or the other.
In my experience, Developers/Business Analysts often tend to think in transaction workflows.
Oracle automatically executes a trigger when a specified event takes place, which may be in the form of a system event or a DML statement being issued against the table. The trigger can be called after the event, to record it, or take some follow-up action.The trigger can be called before the event, to prevent erroneous operations or fix new data so that it conforms to business rules.One use of triggers is to enforce business rules that apply to all client applications.For example, suppose that data added to the table must have a certain format, and that many client applications can add data to this table.
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The separate approach is slightly less risky in case of updates (e.g.