Good book on databases for beginners
It really depends on which flavor of RDBMS you're working with.  Oracle database management is significantly different from SQL Server database management, for instance.

I answered a similar question recently here, but one of the best (Oracle) DBA books that I've read is Darl Kuhn's Pro Oracle Database Administration.  I used it as a textbook in graduate school, and it covers everything from install, config, backups, partitioning, etc, as well as common real-life problems and their solutions.

I wouldn't classify it as being for "beginners", but I had never had any database management before either, and I did ok.