Hibernate ORM

[Muhammad Siddiqur Rahman]

Idiomatic persistence for Java and relational databases.

Hibernate Tutorial
Hibernate is a high-performance Object/Relational persistence and query service which is licensed under the open source GNU Lesser General Public License (LGPL) and is free to download. Hibernate not only takes care of the mapping from Java classes to database tables (and from Java data types to SQL data types), but also provides data query and retrieval facilities.

This tutorial will teach you how to use Hibernate to develop your database based web applications in simple and easy steps.
http://www.tutorialspoint.com/hibernate/