0025028: Default value applied again after updating a numeric field with a trigger

-- Function: c_orderline_test()

-- DROP FUNCTION c_orderline_test();

CREATE OR REPLACE FUNCTION c_orderline_test()
  RETURNS trigger AS
$BODY$ DECLARE 
        
BEGIN
    
    IF AD_isTriggerEnabled()='N' THEN IF TG_OP = 'DELETE' THEN RETURN OLD; ELSE RETURN NEW; END IF; 
    END IF;

    NEW.qtyordered = 3;

IF TG_OP = 'DELETE' THEN RETURN OLD; ELSE RETURN NEW; END IF; 

END 

; $BODY$
  LANGUAGE plpgsql VOLATILE
  COST 100;
ALTER FUNCTION c_orderline_test()
  OWNER TO tad;

CREATE TRIGGER c_orderline_test
  BEFORE INSERT
  ON c_orderline
  FOR EACH ROW
  EXECUTE PROCEDURE c_orderline_test();