SELECT emp_no,manager_no,emp_salary,manager_salary
FROM
(
SELECT de.emp_no,dept_no,salary AS emp_salary
FROM dept_emp AS de INNER JOIN salaries AS s1
ON de.emp_no=s1.emp_no
WHERE de.to_date='9999-01-01'
AND s1.to_date='9999-01-01') AS a
JOIN
(SELECT dm.emp_no AS manager_no,dept_no,salary AS manager_salary
FROM dept_manager AS dm INNER JOIN salaries AS s2
ON dm.emp_no=s2.emp_no
WHERE dm.to_date='9999-01-01'
AND s2.to_date='9999-01-01') AS b
ON a.dept_no=b.dept_no
WHERE emp_salary>manager_salary

建两个虚拟表，
一个表找出员工的工号，工资
一个表找出管理者的工号，工资
然后用join关联两个表
where条件为员工工资大于管理者工资