176. Second Highest Salary.sql

/*
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                 |
+---------------------+
First one create temporary table, second one using IFNULL
*/
# Write your MySQL query statement below
SELECT
    (SELECT DISTINCT Salary FROM Employee
        ORDER BY Salary DESC LIMIT 1 OFFSET 1)
AS SecondHighestSalary


# Write your MySQL query statement below
SELECT
IFNULL( (SELECT DISTINCT Salary FROM Employee ORDER BY Salary DESC LIMIT 1 OFFSET 1), NULL) AS SecondHighestSalary