Hi,

I've read some topics about Hibernate, but It's not clear to me, whether I can use Hibernate for an existing database schema.

We need to migrate an old system to J2EE enviroment. we can't change the database schema, but we can change the application logic.

So we have a lot of tables, complex selects and inserts.
We wan't to design new Java objects, and map them to these given tables.

Is it possible?

Theoretically it is of course possible. But you have to experiment with hibernate a little if your table structure is mappable. If you have very "non-normal-form" tables, you might run into problems, even though Hibernate can really handle a lot. But especially overly complex composite key scenarios and such things may be difficult to map (though not necessarily impossible).

So alltogether: Yes, possible, but you have to do some prototyping first. You could also take a look at midlegen to take the "from the database upwards" approach.

Yes. U can use existing schema. Hibernate supports most of the database operations. For detail information please see documentation(http://www.hibernate.org/5.html)

Thank you for your reply.
I'm quite new to Hibernate. The existing database we have was designed by database professionals. I haven't overviewed the schema, but I believe it's quite normalized, and have no anomalies.

But as we'll create Java objets, probably it won't fit perfectly to the tables. The following situations may occur:
the object has more attributes then the mapped table OR
the object has fewer attrributes OR
Object mapping to multiple tables will be neded (again, we can't change the existing DBS schema)

Do you think that Hibernate can handle this?

Thank you

Yes, with varying degrees of work you have to do yourself.