LeetCode in Kotlin

176. Second Highest Salary

Medium

SQL Schema

Table: Employee

+-------------+------+
| Column Name | Type |
+-------------+------+
| id          | int  |
| salary      | int  |
+-------------+------+
id is the primary key column for this table.
Each row of this table contains information about the salary of an employee. 

Write an SQL query to report the second highest salary from the Employee table. If there is no second highest salary, the query should report null.

The query result format is in the following example.

Example 1:

Input:

Employee table:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
| 2  | 200    |
| 3  | 300    |
+----+--------+

Output:

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

Example 2:

Input:

Employee table:
+----+--------+
| id | salary |
+----+--------+
| 1  | 100    |
+----+--------+

Output:

+---------------------+
| SecondHighestSalary |
+---------------------+
| null                |
+---------------------+

Solution

# Write your MySQL query statement below
SELECT ifnull(
                (SELECT distinct(Salary)
                 FROM Employee
                 ORDER BY Salary DESC
                 LIMIT 1
                 OFFSET 1), NULL) SecondHighestSalary;