combining different levels of a tree

[dbnDavid]

I'm putting together a database for a journal which publishes two issues per
volume. I have a Volumes field in one table containing a record for each
volume in the sequence of volumes, related to an Issues field in a second
table with a record for every issue in the sequence of issues.
Customers/subscribers can order either a volume or a single copy, so I'm
looking for the best way to have "Volume 5" or "Volume 7 no. 2" equally
available as single items for a purchase order. I want to be able to enter an
order for "Volume 5" as an order for a single item, not as an order for two
separate items "Volume 5 no. 1" and "Volume 5 no.2", but I'm finding this
tricky because volumes and issues reside at different levels in a tree. The
tree structure is useful and I'd like to preserve it, but is there a way I
could create a query that would merge volumes and issues into a single list
of sale items available for selection in a single control on an orders form?
I know very little about VBA, but could probably manage to insert a piece of
code if anyone has a suggestion. Thanks.

 

[dbnDavid]

Solved my problem. Found out more about SQL and discovered that the solution
was a very simple SQL Union Query.