Calculating Factorial of a Number in SQL Server 2012

Here, I have constructed a query that provides a solution in SQL Server to determine the factorial of a specified number. If you have programmed in languages like C, C++ or other languages then you are probably familiar with the word factorial. Transact-SQL also gives you this option to repeat the expression using CTE (Common Table Expression). A factorial is denoted by n!. The factorial of a number is defined as n! = 1 * 2 * ... * n.

Let's have a look at a practical example. The example is developed in SQL Server 2012 using the SQL Server Management Studio.

SQL Common Table Expression (CTE)

SQL Server has a very powerful feature that has been added for the programmers' benefit: Common Table Expression (CTE). Common Table Expressions, or CTE, are a new construct introduced in Microsoft SQL Server 2005 that offers a more readable form of the derived table that can be declared once and referenced multiple times in a query.

We have a simple table Employeein our database.

Example

;WITH EmployeeCTE AS
( SELECT [EmpID]
,[EmpName]
,[EmpSalary]
FROM [master].[dbo].[Employee]
WHERE [EmpSalary]>4000
)
SELECT * FROM EmployeeCTE

Now press F5 to execute.

Output

Calculating Factorial of Numbers using CTE

The example of factorial numbers should look as follows:

0! = 1

1! = 1

2! = 2

3! = 6

4! = 24

The following code defines how to find the factorial of a number:

set nocount on
Declare @Number int,@Fact int
set @Fact=1
set @Number =6; -- To Find Factorial of number
WITH Factorial AS -- Defined Common Table Expression
(
SELECT
CASE WHEN @Number<0 THEN NULL ELSE 1 -- To check if number is 0 it will return 1
END N
UNION all
SELECT (N+1)
FROM Factorial
WHERE N < @Number -- To check factorial number with increment number
)
SELECT @Fact = @Fact*N from Factorial -- To repeat the process
select @Number as 'Number', @Fact as 'Factorial' -- To show result
Print 'The factorial of' +SPACE(1) + cast(@Number as varchar(100)) + SPACE(1) + 'is:' + cast(@Fact as varchar(100)) -- To print a message

Output

Calculating Factorial of Numbers using CTE

When you click on the message tab, the following message will be printed:

Output