LC177-第N高的薪水

177. 第N高的薪水

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)
  );
END