LeetCode

     Description：

  Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

  For example, given the above Employee table, the second highest salary is 200. If there is no second highest salary, then the query should return null.

  大意是选出第二高的Salary。

# Write your MySQL query statement below
select max(Salary) from Employee
where
Salary < (select max(Salary) from Employee );