leetcode177-Nth Highest Salary(找出第n大的数据)

问题求解：

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.

问题求解：

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT BEGIN declare n1 int;
    set n1=N-1;
  RETURN (
      # Write your MySQL query statement below.
      select Salary from (select distinct Salary from Employee) t order by Salary desc limit n1,1 );
END