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.
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 | +---------------------+
———————————————- SOLUTION ———————————————-
#Solution 1:
SELECT Max(Salary) SecondHighestSalary
FROM Employee WHERE Salary < (SELECT MAX(Salary) FROM Employee)
#Solution 2:
WITH CTE AS (SELECT DISTINCT Salary
FROM Employee
ORDER BY Salary DESC
LIMIT 2)
SELECT Salary as SecondHighestSalary
FROM CTE
ORDER BY Salary Asc
LIMIT 1;
#Solution 3:
WITH CTE AS
(
SELECT Salary,
DENSE_RANK() OVER (ORDER BY Salary DESC) AS DENSERANK
FROM Employee
)
SELECT Salary SecondHighestSalary
FROM CTE
WHERE DENSERANK = 2;