select e.employee_id,e.manager_id,e.first_name,d.first_name
from employees e,employees d
where e.manager_id=d.employee_id
select e.employee_id,e.manager_id,e.first_name,d.first_name
from employees e,employees d
where d.employee_id=e.manager_id这两种写法区别么
from employees e,employees d
where e.manager_id=d.employee_id
select e.employee_id,e.manager_id,e.first_name,d.first_name
from employees e,employees d
where d.employee_id=e.manager_id这两种写法区别么
(e.manager_id=d.employee_id)== (d.employee_id=e.manager_id)