LeetCode 176. Second Highest Salary--Database--数据库题目

本文链接：https://blog.youkuaiyun.com/zhangpeterx/article/details/100797602

本文详细解析了如何使用SQL查询数据库中员工的第二高薪水，提供了多种解决方案，包括处理无第二高薪水的情况。

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LeetCode 176. Second Highest Salary–Database–数据库题目

LeetCode题解专栏：LeetCode题解
我做的所有的LeetCode的题目都放在这个专栏里，大部分题目Java和Python的解法都有。

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                 |
+---------------------+

题目意思很简单，就是找第二高的工资。

按工资排序的代码如下：

select distinct Salary as SecondHighestSalary
from Employee
order by Salary desc;

找第二高的代码：

select distinct salary as SecondHighestSalary
from Employee
order by salary DESC
limit 1 offset 1;

加上null的处理

select (select distinct salary
from Employee
order by salary DESC
limit 1 offset 1) as SecondHighestSalary;

另外一种解放：

SELECT max(Salary) AS SecondHighestSalary
FROM Employee
WHERE Salary < (SELECT max(Salary) FROM Employee);