Does 3.23 support derived tables (aka inline views)? If so, plug the SELECT statement that would have generated the temp. table directly into your main query, and Bob's your uncle.

I have a feeling that I should be able to write a single query to handle this, but I just can't think of how... Basically, I have two tables: "distributors" and "postalcodes".

When you want to combine values in Microsoft Excel, instead of complex expressions or VBA, opt for Power Query – it’s fast and easy.