LeetCode: 177. Nth Highest Salary

题目描述

Write a SQL query to get the nth highest salary from the ​​Employee​​ table.

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

For example, given the above Employee table, the nth highest salary where ​​n = 2​​​ is ​​200​​​. If there is no nth highest salary, then the query should return ​​null​​.

+------------------------+
| getNthHighestSalary(2) |
+------------------------+
| 200                    |
+------------------------+

解题思路

将员工表按照薪水从高到低排序，取第 ​​n​​ 行数据。

AC 代码

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
  DECLARE TMP INT;
  SET TMP=N-1;
  RETURN (
      # Write your MySQL query statement below.
      SELECT * FROM (SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC) AS So limit TMP,1
  );
END