Factorial: The product of an integer and all the integers below it; e.g. factorial four ( 4! ) is equal to:

To put it in an Oracle PL/SQL code, I would create a function that will take the input of an integer whose factorial is to be calculated and the return value would be the factorial of the given input.

CREATE OR REPLACE FUNCTION GET_FACTORIAL (P_INT NUMBER)
RETURN NUMBER
IS
   P_FACT PLS_INTEGER := 1;
BEGIN
   FOR I IN 1 .. P_INT
   LOOP
     P_FACT := P_FACT * I; 
   END LOOP; 
RETURN P_FACT;
END;
/

The same can now be executed from a select statement as follows:

SELECT GET_FACTORIAL(6) FROM DUAL;

Output: 720