DECLARE @AvailableCount INT

IF @ItemType IS NOT NULL

    BEGIN

        SELECT @AvailableCount=COUNT(SerialNumber.ProductID)-COUNT(Rental.SerialNumber)
        FROM PRODUCT
        INNER JOIN SerialNumber
            ON Product.ProdID=SerialNumber.ProductID
        INNER JOIN Rental
            ON SerialNumber.SerialNumber=Rental.SerialNumber
        WHERE ProdDescription=@ItemType AND @AvailableCount>0
        SELECT COUNT(*) AS 'Number Available', RENTAL.StoreID,ProdDescription, ProdName,ProdSize, ProdFlex, ProdTerrain, ProdAbilityLevel,ProdShape,ProdRocker
        FROM PRODUCT
        INNER JOIN SerialNumber
            ON Product.ProdID=SerialNumber.ProductID
        INNER JOIN Rental
            ON SerialNumber.SerialNumber=Rental.SerialNumber
        WHERE ProdDescription=@ItemType
        GROUP BY RENTAL.StoreID, ProdDescription, ProdName,ProdSize, ProdFlex, ProdTerrain, ProdAbilityLevel,ProdShape,ProdRocker
        ORDER BY 2,1
        RETURN (0);
    END
ELSE
    BEGIN
        PRINT 'Please Enter one of the following Products:
         "Snowboard"
         "Skies"
         "Splitboard"
         "Boots"
         "Goggles"
         "Helmet"