leetcode sql题目

1 
# Write your MySQL query statement below
select max(salary) as SecondHighestSalary 
from Employee 
where salary not in (select max(salary) 
from Employee )

Write a SQL query to get the second highest salary from the Employee table.

+----+--------+
| Id | Salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

For example, given the above Employee table, the query should return 200 as the second highest salary. If there is no second highest salary, then the query shoul