Object-relational database programming
involves making use of relational database from an object programming perspective. This contrasts with both the database and programming language being object-oriented as well as with both the database and language being procedural.
A very popular object-relational technology for Perl is Class::DBI. A popular purely procedural technology for Perl is DBIx::Recordset. A popular (yay, perhaps the only) object-oriented database and Perl module is Ace.
If you had a database-driven project to do from scratch which of these 3 routes would you take and why? I guess my thinking on the matter is that the object-relational approach is a compromise: if you wanted to be object-oriented in the language, why not in the database as well? On the other hand, perhaps what I see as a mismatch is really a synergy: perhaps there is something powerful to be gained from the marriage of apparently different paradigms of thought. Perhaps object-relational mismatch is not as big a deal as the gains.