If you're asking which database to use with Perl, that's a decision that is constrained by any of the following: you, your team, your boss, your DBA, your service provider, and your financial capacity.

There are number of OpenSource or otherwise free databases out there. MySQL, and PostgreSQL are among the common ones in this category. PostgreSQL seems to be more advanced, while MySQL is more likely to already be installed on your Linux system. For lightweight work there is also SQLite, which stores its databases as single files.

Instead of getting into the nearly religious zealotry pitching one DB over another, I can point you to Wikipedia's article comparing relational databases. You would have to also check the CPAN to verify that there is a Perl Database Driver (DBD::???) for the database you're considering.

The canonical way to access a database with Perl is to install DBI, as well as the DBD for the specific database you're targeting (DBD::mysql, for example). If you want an object-oriented approach to dealing with the database, also install DBIx::Class and start reading its POD.

Hope this helps...