Second Highest Salary

Task: Write a solution to find the second highest salary from the Employee table. If there is no second highest salary, return null.

Table: Employee

+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | INT  |
| salary      | INT  |
+-------------+------+

Input: Employee table:

+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

Output:

+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+