ODBC / DBClient

I'm using the Informix db as a backend for a software product I'm using; however, a number of people have asked that I be able to speak with *any* (in theory) database should the need arise (multiple site access or just a premade vendor choice). I notice Informix claims to have ODBC support and was wondering if anyone had some insights or experience with ODBC or DBClient -- basically I need something that will enable a db client to (preferably programatically, like ESQL/C) speak with any db using a relatively standard interface. Any information would be greatly appreciated. -Jason