/*
Second Highest Salary

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.

+---------------------+
| SecondHighestSalary |
+---------------------+
| 200                 |
+---------------------+
*/

SELECT IFNULL(
    (
        SELECT DISTINCT(Salary)
        FROM employee
        ORDER BY employee.Salary DESC
        LIMIT 1
        OFFSET 1    
    ), NULL) AS "SecondHighestSalary"