This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
If you want to try JDBC only (not Oracle specific features), there are other options with lesser memory footprints like HSQLDB, Derby etc which are absolute free. Coming to Oracle, I think you can still download a trial version of it.