先查员工的薪水 再查manager的薪水 之后对比大小

select a1.emp_no emp_no,a2.emp_no manager_no,a1.salary emp_salary,a2.salary manager_salary
from
(select de.emp_no,de.dept_no,sa.salary
from dept_emp de join salaries sa
on de.emp_no = sa.emp_no) a1
join
(select de.emp_no,de.dept_no,sa.salary
from dept_emp de join salaries sa
on de.emp_no = sa.emp_no
where de.emp_no in (select emp_no
from dept_manager)) a2
on a1.dept_no = a2.dept_no
where a1.salary > a2.salary;