177. 第 N 高的薪水

English Version

题目描述

表: Employee

+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| salary      | int  |
+-------------+------+
Id是该表的主键列。
该表的每一行都包含有关员工工资的信息。

 

编写一个SQL查询来报告 Employee 表中第 n 高的工资。如果没有第 n 个最高工资，查询应该报告为 null 。

查询结果格式如下所示。

 

示例 1:

输入: 
Employee table:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+
n = 2
输出: 
+------------------------+
| getNthHighestSalary(2) |
+------------------------+
| 200                    |
+------------------------+

示例 2:

输入: 
Employee 表:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
+----+--------+
n = 2
输出: 
+------------------------+
| getNthHighestSalary(2) |
+------------------------+
| null                   |
+------------------------+

解法

SQL

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
    SET N = N - 1;
  RETURN (
      # Write your MySQL query statement below.
      SELECT (
          SELECT DISTINCT Salary
          FROM Employee
          ORDER BY Salary DESC
          LIMIT 1 OFFSET N
      )
  );
END