A ORM implementation is a complex beast - less complex than an application server, but more complex than a web application framework like Struts. Why should we introduce another complex infrastructural element into our system?Will it be worth it?
A supposed advantage of ORM (object/relational mapping) is that it shields developers from messy SQL.
Now, let's look at some of the benefits of ORM and Hibernate:
Productivity: Persistence-related code can be perhaps the most tedious code in a Java application. Hibernate eliminates much of the grunt work and lets you concentrate on the business problem -No matter which application-development strategy you prefer - top-down, starting with a domain model, or bottom-up, starting with an existing database schema.
Maintainability: Fewer lines of code(LOC) make the system more understandable, because it emphasizes business logic rather than plumbing. In systems with hand-coded persistence, an inevitable tension exists between the relational representation and the object model implementing the domain. Changes to one always involve changes to the others. ORM provides a buffer between the two models, allowing more elegant use of object orientation on the Java side, and insulating each model from minor changes to the other.
Performance: The people who implemented your ORM software had much more time to investigate the performance optimizations than you have.
Vendor independence: An ORM abstracts your application away from the underlying SQL database and SQL dialect.
I really don't want to use SQL again and again even for very simple relationship project. Hibernate will help to mediate the application's interaction with a relational database, leaving the developer free to concentrate on the business problem at hand.