Searching for Null Values IN DataAssist

Hi,

I ran the search wizard for DataAssist and then joined two tables, created a date range and included some AS statements.

Here is what my query currently looks like:

SELECT inventory.itemId AS Item_ID, inventory.itemName AS Item, inventory.itemDesc AS Description, inventory.itemSize AS Size, inventory.itemColor AS Color, inventory.partNum AS Part_Number, inventory.prodLine AS Product_Line, inventory.itemPrice AS Price, inventory.itemQty AS Quantity_Available, (inventory.itemQty*inventory.itemPrice)AS Total_Value_of_Available, SUM(orderdetails.DetailQuantity)AS Quantity_Sold, SUM(orderdetails.DetailQuantity*inventory.itemPrice)AS Total_Value_of_Usage
FROM orderdetails INNER JOIN inventory ON orderdetails.DetailItemId = inventory.itemId INNER JOIN orders ON orderdetails.DetailOrderId = orders.OrderId
GROUP BY inventory.itemId
ORDER BY inventory.itemName ASC

My issue is, how to have items that were not sold during the selected date range, to also appear on the results page? So...if there was not a particular Part_Number listed from the orderdetails table, during the date range that was selected, but still listed in inventory, it would still show up on my results page.

Can you please advise me as to how to search for "NULL" values and still have them appear?

Thanks!