177 Nth Highest Salary 第N高的薪水
Description:
Write a SQL query to get the nth highest salary from the Employee table.
+----+--------+
| Id | Salary |
+----+--------+
| 1 | 100 |
| 2 | 200 |
| 3 | 300 |
+----+--------+
Example:
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.
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+
题目描述:
编写一个 SQL 查询，获取 Employee 表中第 n 高的薪水（Salary）。
+----+--------+
| Id | Salary |
+----+--------+
| 1 | 100 |
| 2 | 200 |
| 3 | 300 |
+----+--------+
示例 :
例如上述 Employee 表，n = 2 时，应返回第二高的薪水 200。如果不存在第 n 高的薪水，那么查询应返回 null。
+---------------------+
| SecondHighestSalary |
+---------------------+
| 200 |
+---------------------+
思路:
DISTINCT
LIMIT
IFNULL
DESC
代码:
MySQL:
CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
SET N = N - 1;
RETURN (
# Write your MySQL query statement below.
SELECT IFNULL((SELECT DISTINCT SALARY FROM EMPLOYEE ORDER BY SALARY DESC LIMIT N, 1), NULL)
);
END
