You're right that there isn't a great way to join tables with Airtable's API. The closest you can get is to use a linked record field, which acts as a pointer to another record. You still end up with the problem you mentioned of having to run another query on the second table separately.

Your best bet is to stick with an actual SQL database. Using an ORM should make your life significantly easier so you don't actually have to write raw SQL. If you still want a graphical interface to your data, BaseDash lets you view and edit SQL databases just like Airtable. A full API with join support is coming soon, so that could be your perfect solution to this problem.