select de.emp_no, dm.emp_no as manager_no,
    s1.salary as emp_salary, 
    s2.salary as manager_salary
    from dept_emp de 
    join dept_manager dm on de.dept_no = dm.dept_no
    join salaries s1 on de.emp_no = s1.emp_no
    join salaries s2 on dm.emp_no = s2.emp_no
    where s1.salary > s2.salary

这题没啥思路，重点在于两次连接salaries表，一次用于取员工工资，一次用于取领到工资，取完之后再加上条件员工工资>领导工资