Second Highest Salary

Moderate
0/80
Average time to solve is 20m

Problem statement 

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 should return null.

+---------------------+
| salary              |
+---------------------+
| 200                 |
+---------------------+
Solution
(100% EXP penalty)
Second Highest Salary
Console