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)×…×2×1Code language: SQL (Structured Query Language) (sql)

By convention, 0! = 1.

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

factorial(n)Code language: SQL (Structured Query Language) (sql)

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 undefinedCode language: plaintext (plaintext)

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);Code language: SQL (Structured Query Language) (sql)

Output:

 factorial
-----------
       120
(1 row)Code language: SQL (Structured Query Language) (sql)

Summary

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