如何使用条件显示所有记录，包括在Manager_ID中具有零值的记录？

Question

如何使用条件显示所有记录，包括在Manager_ID中具有零值的记录？

select e.last_name as Employee, e.employee_id as Emp#, d.last_name as Manager, d.employee_id as Mngr#
from hr.employees e, hr.employees d
where e.manager_id = d.employee_id
and e.manager_id is null;

Answer 1

您正在寻找的是

enter image description here
select e.last_name as Employee, e.employee_id as Emp#, d.last_name as Manager, d.employee_id as Mngr#
from hr.employees e left join hr.employees d
on e.manager_id = d.employee_id;