The previous three chapters employed individual, ‘flat’ files to provide persistent data storage. Nowadays, of course, most organisations have the bulk of their data structured into databases, which often need to be accessed from more than one site. These databases are almost invariably relational databases. Programs written in Java are able to communicate with relational databases (whether local or remote) via the Java Database Connectivity (JDBC) API, which became part of the core Java distribution with JDK 1.1. In this chapter, we shall consider how such databases may be accessed via JDBC.