CREATE OR REPLACE TRIGGER orders_before_update
BEFORE UPDATE
ON orders
FOR EACH ROW

DECLARE
v_username varchar2(10);

BEGIN

-- Find username of person performing UPDATE on the table
SELECT user INTO v_username
FROM dual;

-- Update updated_date field to current system date
:new.updated_date := sysdate;

-- Update updated_by field to the username of the person performing the UPDATE
:new.updated_by := v_username;

END;