【SQL】177. Nth Highest Salary

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.

 CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
 BEGIN
   set N=N-1;
   RETURN (
       # Write your MySQL query statement below.
       select distinct Salary
       from Employee
       order by Salary desc
       limit N,1
   );
 END