Is there an open source "object to db" handler?

[mark baum]

Hi,
I'm just finishing a prototype application that stores the data in a db with JDBC. It was a good exercise that I wouldn't miss, but it took me much more time to find the typos in the SQL commands then to program the logic. Because this is so error proune and time consuming and eventually is a rather schematic work, I wonder if anybody knows (or has made o a tool, that reads and writes data transparently. (I read about the Java Blend, but the prices knocked me out - and it isn't even marketed anymore).
Thanks for help