These documents contain information about forms, and reports, and the properties of a data source.
The database document contains no data per default. The following is stored inside the document:
Forms
Reports
The table settings defined in DataSettings
The query settings defined in DataSettings
All properties of the service DataSource
That the interface ::com::sun::star::view::XPrintable is not optional at the
::com::sun::star::document::OfficeDocument service is a documenation problem.
The service OfficeDatabaseDocument doesn't support any printing.