I'm not sure building queries for each database is going to be productive. From a 'Get it done' approach, I'd suggest just using DBI and standard, no frills, Lowest Common Denominator SQL.

For the more adventurous approach, you could use Class::DBI or DBIx::Class, and write the SQL programmatically.

A third approach would be to build a class that gives you the appropriate query or command for a particular search or action. The default would be the plain SQL, and the exception would be the SQL coded for a specific database. But that sounds like a fair bit of work.

So let my ask one of my favourite questions: What problem are you trying to solve?