Example 1-19 Creating a Database Trigger

CREATE TABLE emp_audit ( emp_audit_id NUMBER(6), up_date DATE, 
                         new_sal NUMBER(8,2), old_sal NUMBER(8,2) );

CREATE OR REPLACE TRIGGER audit_sal
   AFTER UPDATE OF salary ON employees FOR EACH ROW
BEGIN
-- bind variables are used here for values
   INSERT INTO emp_audit VALUES( :old.employee_id, SYSDATE, 
                                 :new.salary, :old.salary );
END;
/