There a number of pure Java SQL database systems develolpers can embed into applications. In this tip we introduce two open source projects, HSQLDB and Apache Derby.

Java Database Connectivity: Struts applications can make use of the core JDBC API to interact with relational databases. JDBC provides a low-level interface for executing SQL queries, managing ...

Here's a quick JDBC with HSQLDB tutorial to get you up and running with Java database connectivity and the popular HyperSQL database.