题目描述：

https://leetcode-cn.com/problems/second-highest-salary/

 

方法一：

select (select distinct Salary from Employee order by Salary desc limit 1,1) as SecondHighestSalary;

 

方法二：

select max(Salary) as SecondHighestSalary from
(select Salary from Employee where Salary!=(select max(Salary) from Employee)) tmp;

 

修订版：

select max(Salary) SecondHighestSalary
from Employee
where Salary!=(select max(Salary) from Employee);