LeetCode-SQL-177-第N高的薪水

177. 第N高的薪水

编写一个 SQL 查询，获取 Employee 表中第 n 高的薪水（Salary）。

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
SET n = N-1;
  RETURN (     
  SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT n,1
  );
END

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
  RETURN (     
  SELECT  IF(count<N,NULL,min) 
  FROM
    (SELECT MIN(Salary) AS min, COUNT(1) AS count
    FROM
      (SELECT DISTINCT Salary
      FROM Employee ORDER BY Salary DESC LIMIT N) AS a
    ) as b
  );
END