[LeetCode]-DataBase-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.

需求：查询第N高的工资

CREATE TABLE Employee(
Id TINYINT UNSIGNED,
Salary DECIMAL(10,2)
)ENGINE=MyISAM CHARSET=utf8;

-- sql 使用 limit 和 ORDER BY
DROP FUNCTION IF EXISTS getNthHighestSalary;
CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE m INT;
SET m = n -1;
RETURN (
# Write your MySQL query statement below.
SELECT DISTINCT salary FROM employee ORDER BY salary DESC LIMIT m,1
);
END