The easiest method to do this is to use DBD::ODBC and create a system DSN. Simply provide the DSN name along with username and password to the DBI and you have your DB object to play with.

The advantage, then, is that when you go live you can create a system dsn on the live machine(s) that has the same name but points to your production db. You also don't have to embed the server IP or database name in your code. They are in the DSN.

It also means no code changes are required unless your u/n, p/w or the dsn name changes.