找第二大的数SQL-Second Highest Salary

1： 找小于最大的最大的

select max(Salary) from Employee where Salary<(select MAX(Salary) from Employee);

2. 排序

select  Salary from Employee where Salary not in (select MAX(Salary)from Employee) order by Salary desc limit 1;

select (

select distinct Salary from Employee order by Salary Desc limit 1 offset 1

) as SecondHeighestSalary;

找第n个数：

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT;
set N=N-1;
  RETURN (

      # Write your MySQL query statement below.
      select  Salary from Employee order by Salary desc limit 1 offset N
  );
END

CREATE FUNCTION getNthHighestSalary(N INT) RETURNS INT
BEGIN
DECLARE M INT;
set N=N-1;
  RETURN (

      # Write your MySQL query statement below.
      select  distinct Salary from Employee order by Salary desc limit 1 offset N
  );
END

　　不能在limit 里N-1， 因为limit里不计算

哈哈： distinct ：在表中可能包含重复值，返回唯一不同的值，