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 second highest salary is 200. If there is no second highest salary, then the query should return null.
1 SELECT DISTINCT Salary AS SecondHighestSalary 2 FROM Employee 3 UNION SELECT null 4 ORDER BY SecondHighestSalary DESC 5 LIMIT 1,1;