查 n 高的薪水，这种写法的优点 ？

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
    SET N := N-1;
  RETURN (
      SELECT 
            salary
      FROM 
            employee
      GROUP BY 
            salary
      ORDER BY 
            salary DESC
      LIMIT N, 1
  );
END

select getNthHighestSalary(2);Copy

SELECT `id`,`salary` FROM `employee` ORDER BY `salary` DESC LIMIT 1 OFFSET n-1;Copy