I really enjoy database design and the whole concept of managing data semantically and all the logic that comes with it.
My knowledge level when it comes to databases is
A very common scenario is having to map ugly databases to an entity model which is not necessary reflected directly in the structure of the DB. Working out which way is best to model the data in your domain can be tricky.
Full text search and XML are subjects that seem to be coming up more and more.
I have no experience with it but I know DB2 (of which there is a trial version) has some crazy new features)
Have fun :-)