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 |
+----+--------+
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。
+------------------------+
| getNthHighestSalary(2) |
+------------------------+
| 200 |
+------------------------+
Solution:
CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
Declare M int;
Set M = N-1;
RETURN (
# Write your MySQL query statement below.
select IFNULL((select distinct Salary from Employee order by Salary DESC limit M,1),NULL) AS getNthHighestSalary
);
END