This is the reference guide for DatabaseLayer component. The DatabaseLayer classes provide a database independent interface similar to JDBC (but only VERY basic functionality). So far, the only database backends supported are SQLite3, Firebird, MySQL, and Postgresql. Although the C++ interface can be common between database, it should be noted that the SQL understood by the different database backends may vary.
Currently there is not a full tutorial but the usage of DatabaseLayer classes is pretty easy; just take a look at the DatabaseLayer sample page to get an idea. A summary of the DatabaseLayer functionality can be found on the Functionality Summary page.
To build DatabaseLayer and integrate it in your program, look at the Compiling DatabaseLayer page.