Reason of choosing Hibernate
1) Hibernate provides all above O/R benefits. (Productivity, Maintainability, Portability).
2) Hibernate is free and open source – Cost Effective
3) Hibernate learning curve is short. Since we all have working experience in using Hibernate, and Hibernate is totally object orientated concept, it will shorted our learning curve.
4) Hibernate tools provided by community helps developer generate or develop hibernate application very fast and easy. (Eclipse’s Plugin & Code generation tools)
5) Hibernate is popular, when we goes wrong with Hibernate, we can easily find the answer from Google. In addition, there are many books, communities and forums on Hibernate.

Hibernate

Hibernate's primary feature is mapping from Java classes to database tables (and from Java data types to SQL data types). Hibernate also provides data query and retrieval facilities. Hibernate generates the SQL calls and relieves the developer from manual result set handling and object conversion, keeping the application portable to all supported SQL databases, with database portability delivered at very little performance overhead.