I did not think of Product as part when I posted my response. I just posted
self-join for someone and think it might apply here.

A Parts list to have a Foreign Key field for Product. Products could
themselves be parts and be in a one-to-many relationship with parts.
In the Relationship window add the table twice (Access adds a sufix of '_1'
to the table name of the second object.).
Click on the Primay Key field of first table and drag to the Foreign Key
field of the second table. Select Referential Integerity and Cascade Updates.

--
Build a little, test a little.


"Fred" wrote:

I hadn't seen Karl's response when I wrote mine.

His is more simpler and more straightforward (= better) if you have two
clear tiers (products and parts) which are distinct from each other.

Mine is messier but deals with multi-level Bills of Material, and products
and where each "product" is also a part. That's the case at our company.

Fred