sql

Create table If Not Exists Employee (Id int, Salary int)
Truncate table Employee
insert into Employee (Id, Salary) values ('1', '100')
insert into Employee (Id, Salary) values ('2', '200')
insert into Employee (Id, Salary) values ('3', '300')

编写一个 SQL 查询，获取 Employee 表中第二高的薪水（Salary） 。

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

 

例如上述 Employee 表，SQL查询应该返回 200 作为第二高的薪水。如果不存在第二高的薪水，那么查询应返回 null。

+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+        

解答：

　　

SELECT
    (SELECT DISTINCT
            Salary
        FROM
            Employee
        ORDER BY Salary DESC
        LIMIT 1 OFFSET 1) AS SecondHighestSalary


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


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

　　

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/second-highest-salary
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