CREATE OR REPLACE TRIGGER TRIGGER_EMP_AUDIT
AFTER UPDATE OF SALARY ON EMPLOYEES
FOR EACH ROW
DECLARE
V_SALARIO_ANTERIOR EMPLOYEES.SALARY%TYPE:= 0;
BEGIN
SELECT SALARY INTO V_SALARIO_ANTERIOR FROM EMPLOYEES WHERE EMPLOYEE_ID = :NEW.EMPLOYEE_ID;
IF :OLD.SALARY != :NEW.SALARY THEN
INSERT INTO EMP_AUDIT (EMPLOYEE_ID, AUDIT_TIMESTAMP, AUDIT_MESSAGE)
VALUES (:NEW.EMPLOYEE_ID, SYSTIMESTAMP, 'El salario anterior era : ' || V_SALARIO_ANTERIOR || ' ahora es : ' || :NEW.SALARY);
END IF;
END TRIGGER_EMP_AUDIT;