PostgreSQL FACTORIAL() Function

Summary: in this tutorial, you will learn how to use the PostgreSQL factorial() function to calculate the factorial of a number.

Introduction to the PostgreSQL factorial() function

The factorial of a non-negative integer n is the product of all positive integers less than or equal to n:

n!=n×(n−1)×(n−2)×…×2×1

By convention, 0! = 1.

In PostgreSQL, you can use the built-in factorial() function to calculate the factorial of a number:

factorial(n)

In this syntax, n is the number that you want to calculate the factorial. The factorial() function returns null if n is null.

If n is negative, the factorial() function will issue an error:

ERROR:  factorial of a negative number is undefined

PostgreSQL factorial() function example

Let’s take some examples of using the factorial() function.

The following example uses the factorial() function to calculate the factorial of the number 10:

SELECT factorial(5);

Output:

factorial
-----------
       120
(1 row)

Summary

• Use the factorial() function to calculate the factorial of a number.