351数据库查询，第二高的薪水

Posted 2022-01-17 huoyingfans

力扣

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

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# Write your mysql query statement below select Salary SecondHighestSalary from Employee where Salary<( select max(Salary) from Employee ) order by Salary desc limit 0,1;

问题

输入：

"headers":"Employee":["id","salary"],"rows":"Employee":[[1,100]]

输出：

"headers": ["SecondHighestSalary"], "values": []

预期结果：

"headers":["SecondHighestSalary"],"values":[[null]]

主要难点在这个 null

# Write your MySQL query statement below select IFNULL(Salary,null) SecondHighestSalary from Employee where Salary<( select max(Salary) from Employee ) order by Salary desc limit 0,1;

最简单好理解的

select max(Salary) SecondHighestSalary from employee where salary<(select max(salary) from employee)