Query cannot be updated because the FROM clause is not a single simple

I am trying to update a record that happens to span across two tables.
My tables are Products and Stock and I am using a select query similar to the following:
SELECT

Products.ProductCode,

Products.Description,

Stock.Quantity

FROM Products, Stock

WHERE Stock.ProductCode = Product.ProductCode AND Stock.Quantity <> 0
I have created an edit page but when I try to update a field (e.g. Description) I get the following error:

<<< Record was NOT edited >>>
Query cannot be updated because the FROM clause is not a single simple table name.

It seems the only way that I can resolve this issue is by amending the SQL to not include the second table (Stock).
Please could you advise as to how I can remove the second table from my FROM clause? Or, if this isn't the way to do it, what other options do I have?
Thanks in anticipation.