Dan Thomas (“Danny-T”) has written up a nice concise intro to database concepts, geared toward working with databases in AIR. He ends it with a nice list of factors to consider in deciding whether to use a local database (with AIR’s local SQL database engine) or a remote database (available through the same mechanisms you’d use in a browser-based Flex/Ajax app).

I definitely agree with his conclusion – one of the strengths of AIR is that you can use either, or both, of these approaches depending on the needs of your app.

As a side note, the AIR documentation also includes some introductory content on relational databases, SQL, and related concepts – although I intentionally kept it limited, since the topic of relational databases is so vast that many books have been written about the subject.