Recursive Factorial Function ( n ! )

CREATE Function N_Faktorial
(@Input INT)
RETURNS NUMERIC(38,0)
BEGIN 

DECLARE @Output NUMERIC(38,0)
SET @Output = @Input

IF @Input = 0

BEGIN
SET @Output = 1
RETURN @Output
END

ELSE 

BEGIN
SET @Output = @Output * dbo.N_Faktorial(@Output-1)
END

RETURN @Output

END

-- SELECT dbo.N_Faktorial(5)