It seems the field of databases is constantly changing.
As such, what would you recommend someone just getting into website coding and applications should study as their first database, and why?
Are there any databases a beginner should avoid for a while?
Any on the downswing so heavily that maybe they should not be bothered with at all?
It does a lot of things right, it's open-source, and it's mainstream enough that there's plenty of learning material online and plenty of job opportunities if that's a concern.