DB2 - create user defined function to find out factorial

To find out the factorial of a given number, the below is the useful code to write UDFs in DB2.....

CREATE FUNCTION FACT (NUM INT)
RETURNS INTEGER
SPECIFIC FACTORIAL
BEGIN
	DECLARE V_FACT INT DEFAULT 1;
	IF NUM = 0 THEN
	  RETURN 1;
	ELSEIF NUM >=1 THEN 
	  WHILE (NUM >0) DO
		SET V_FACT = V_FACT * NUM;
		SET NUM = NUM - 1;
	  END WHILE;
	  RETURN V_FACT;
	ELSE 
	  RETURN -1;
	END IF;
END@

-- Test the function
SELECT FACT (10) FROM SYSIBM.SYSDUMMY1