Hi,

I am working on a large (enterprise scale) project. I recently downloaded Hibernate 2.1 and read its documentation and examples. I still have couple of questions unanswered:

1> Entity Beans vs Hibernate:
- What does Hibernate have that Entity Beans can NOT offer?
- What do Entity Beans have that Hibernate can NOT offer?

I am particularly interested in ability to query or update tables from multiple databases (databases hosted on different database servers in different countries) in one EJB transaction.
(* An interesting thing is, some databases still don't support 2-phase commit.)

2> HQL / Database capabilities:
- Can you maintain foreign keys across databases using Hibernate classes?
- Does HQL support joining tables from different databases?

For example, assuming table1 in database1 and table2 in database2; will following query work?
SELECT table1.col1, table2.col2
FROM table1, table2
WHERE table1.col3 = table2.col3
Some databases like Oracle, MS SQL Server (and more) support cross database joins. But does Hibernate support it in HQL?

Thanks for your time,
- Hrishi

Hibernate uses JDBC, so you have all (well, mostly) of the JDBC features and SQL features. Just join your databases at the database level.

Thanks for the reply, Christian.

>Hibernate uses JDBC, so you have all (well, mostly) of the JDBC features and SQL features.

Well, that explains it.

>Just join your databases at the database level.

Could you please ellaborate a little more on "join your databases at the database level"? How to do that / where can I find such example or documentation?

(If this is going out of scope of Hibernate, may be point me in the correct direction).

Thanks again,
- Hrishi

The manual of your database and "views".