NClassifier Usage Examples
Right now, I don't have any examples. However, some examples of Classifier4J's usage can be found here. Everything but Java nuances (such as the Java community's tendency to lean toward lower-case class names, etc.) will work exactly as on that page.
Chances are, by comparing notes between Classifier4J's database usage examples and looking at the source code of NClassifier, you'll be able to easily see how to implement a database backend for use with the Bayesian classifier. If you can't gut through it, I'll have some examples up shortly.