创建触发器MySQL更新员工表中的工资

Question

如何创建触发器MySQL更新员工表中的薪水并将薪金列中的旧值替换为old_salary列？

Answer 1

见CREATE TRIGGER Syntax：

create trigger salary_trigger 
    before update on employee 
    for each row begin 
     if new.salary != old.salary then 
      set new.old_salary = old.salary 
     end if; 
    end;