DBI now (version 1.42 and higher) comes with a very simple but usable database that does not require any other installation other than core Perl and the DBI distribution itself - DBD::DBM. It is built on top of DBD::File and DBI::SQL::Nano, now both also in the DBI distribution. So DBD::DBM is an option if your goal is to be able to create, populate, modify, and query a simple database with DBI and SQL but without requiring any other installations.

If your goal is test without complicating IO issues, you can use DBD::AnyData (the successor of DBD::RAM) in RAM-storage mode which will allow you to do DBI/SQL operations on in-memory databases without any file IO.

If there are other things you are wanting that these don't accomplish, can you be more specific about what you'd want to support?