LeetCode176——第二高的薪水

题目描述

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                 |

+---------------------+

select Salary from Employee

  order by Salary desc

  limit 1, 1;

select Salary from Employee

  group by Salary

  order by Salary desc

  limit 1, 1;

select

  ifnull(

    (select Salary from Employee group by Salary order by Salary desc limit 1, 1),

    null

  ) as SecondHighestSalary;

可以简写为

select

  (select Salary from Employee group by Salary order by Salary desc limit 1, 1)

  as SecondHighestSalary;