Before the DBAL will do anything different for you than just connecting to the default database you will have to configure it. By default it connects using the "native" handler type - which means direct interaction with MySQL.
Since the DBAL offers to store information in multiple sources and not just a single database you might have to understand handlers first.
First, some definitions:
- handler type - which kind of interface is used for a data handler.
The options are "native", "adodb" or "userdefined".
- native - Connects directly to MySQL with hardcoded PHP functions
- adodb - Is an instance of ADOdb database API offering support for a long list of databases other than MySQL. The DBAL extension has been developed with a focus on ADOdb until now, so it should work.
- userdefined - Is an instance of a userdefined class which must contain certain functions to supply results from the "database" - offers support for just any kind of data source you can program an interface to yourself!
- handlerKey - a string which uniquely identifies a data handler. Each handler represents an instance of a handler type (see above). The handlerKey can be any alphanumeric string. The handler key "_DEFAULT" is the default handler for all tables unless otherwise configured.
- tablename - the database table name seen from the TYPO3 side in the system (might differ from the real database name if mapping is enabled!)