获取薪水第二多的员工的empno以及其对应的薪水salary
获取当前薪水第二多的员工的emp_no以及其对应的薪水salary
https://www.nowcoder.com/practice/c1472daba75d4635b7f8540b837cc719
select emp_no, salary, last_name, first_name from employees left join salaries using(emp_no) where salary=(select max(salary) from salaries where salary<(select max(salary) from salaries)) /*排除掉第一最大值,选第二最大值。*/