触发器学习笔记(:new，:old用法)(二)
二者都不能对old 进行修改
*/
create or replace trigger tri_emp2
before update on dept2 for each row
begin
:NEW.deptno := 80;
update emp2 e set e.deptno = :NEW.deptno where e.deptno = :OLD.deptno;
end;