Thinking about an open-source database? (Now that SQL Express is available, I probably wouldn’t even consider an open-source database anymore. But that’s a separate discussion.) If so, I encourage you to take a look at what Computer Associates is doing in the open-source database space with Ingres.
Ingres is a powerful database platform that has been in use at customer sites for decades. It contains all the features you’d expect from a true relational database platform. In fact, Ingres and the popular open-source database, PostgreSQL, share a common heritage. And because Ingres is owned by CA, despite being open-source, there’s no question about where you can get support services for the product or how to get high-quality consulting services for the platform. (Two key problems with open-source databases is figuring out where to buy service and support from.)
So, when it comes to a free, strong, and disposable desktop database—SQL Express is absolutely the way to go. But if you’re unwilling or unable to pony up for a commercial database, but need enterprise database features and scalability, I’d go with Ingres.
Hope this helps,