176. Second Highest Salary.md

176. Second Highest Salary

1. Description

SQL Schema:

CREATE TABLE IF NOT EXISTS Employee (id int, salary int)
TRUNCATE TABLE Employee
INSERT INTO Employee (id, salary)
    VALUES ('1', '100')
INSERT INTO Employee (id, salary)
    VALUES ('2', '200')
INSERT INTO Employee (id, salary)
    VALUES ('3', '300')

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                |
+---------------------+

2. Solutions

Solution 1: Language: SQL

Note if there is no second highest salary, the query should report null. This means we have to return a table that contains the value null. That is why we need an outer SELECT ... AS ....

• Friday, 18 November, 2022
• Runtime: 215 ms, faster than 98.49% of MySQL online submissions for Second Highest Salary.

SELECT (
    SELECT salary FROM Employee
    GROUP BY salary
    ORDER BY salary DESC
    LIMIT 1 OFFSET 1
) AS SecondHighestSalary;