1、查询薪水最大值
select max(salary) as max_salary from salaries2、在薪水表中查询薪水小于1表值的最大值,即为薪水第二多的值
select max(salary) from salaries where salary< (select max(salary) as max_salary from salaries)3、员工表与薪水表连接,筛选薪水等于2表值的员工信息
select a.emp_no,a.salary,b.last_name,b.first_name from salaries as a join employees as b on a.emp_no=b.emp_no where salary= (select max(salary) from salaries where salary< (select max(salary) as max_salary from salaries))