这题以哪个表作为驱动表可以考虑一下

select b.*,a.dept_no
from dept_manager a 
left join  salaries b 
on a.emp_no = b.emp_no
order by b.emp_no


select a.*,b.dept_no
from salaries a
left join dept_manager  b
on a.emp_no = b.emp_no
where b.dept_no is not null
order by a.emp_no