获取员工其当前的薪水比其manager当前薪水还高的相关信息

select salaries.emp_no, a.manager_no, salaries.salary as emp_salary, a.manager_salary
from dept_emp 
left join 
(select d.dept_no as dept_no, d.emp_no as manager_no, s.salary as manager_salary
from salaries as s inner join dept_manager as d 
 on d.emp_no = s.emp_no) a
on dept_emp.dept_no = a.dept_no
left join salaries on dept_emp.emp_no = salaries.emp_no
where salaries.salary > a.manager_salary

1. 从部门经理表dept_manager与薪水表salaries中查询出每个部门的经理薪水（dept_no, manager_no, manager_salary），得到临时表a
2. 部门关系表dept_emp、临时表a和薪水表salaries三表关联，查出该部门中大于部门经理薪水的员工信息