LeetCode: 176. Second Highest Salary
题目描述
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 query should return 200 as the second highest salary. If there is no second highest salary, then the query should return null.
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+解题思路
首先找到最高薪水，然后将最高薪水表和薪水表连接。在新表中 Salary < SecondHighestSalary 的最大值就是所求的第二高薪水。
AC 代码
# Write your MySQL query statement below
select
MAX(Salary) as SecondHighestSalary
from
(select MAX(Salary) as HighestSalary from Employee) as HS, -- 最高薪水表
Employee as E
where HS.HighestSalary > E.Salary;