题解 | #获取当前薪水第二多的员工的emp_no以及其对应的薪水salary#

-- select max(sa.salaries) from employees em join salaries sa on em.emp_no=sa.emp_no
select em.emp_no,mt.salary,em.last_name,em.first_name from employees em join (SELECT emp_no,salary from salaries where 
                salary=(SELECT max(salary) as maxS from  salaries WHERE salary!=(SELECT max(salary) from salaries) 
                  ))as mt on mt.emp_no=em.emp_no  -- where m_t.emp_no=em.emp_no

去除一个最高的 再求最高的，然后再join