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Calculating Factorial of a Number in SQL Server 2012

Posted by Rohatash Kumar Articles | SQL Server November 29, 2012
Here, I have constructed a query that provides a solution in SQL Server to determine the factorial of a specified number.
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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 Employee in our database.

Employee-table-in-Sql-Server.jpg

Example

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

Now press F5 to execute.

Output

CTE-in-Sql-Server.jpg

Calculating Factorial of Numbers using Common Table Expression

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 

 

Factorail-result-in-sql-server.jpg

 

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

 

Output

Factorail-result--message-in-sql-server.jpg

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