is it possible to work on hibernate with different databases ?
Depending on the user, I would work on database1 or database2.
If it's possible, how can I do that.

Yes this is very possible. What is your environment? Are you using JBoss or just standalone Hibernate?

You will need to have seperate configurations (xml or properties files) for each database that you will be using. For each of these configurations you will generate a SessionFactory that could be stored into a Map with some key. When your user executes a request for information from the database, you simply can just do a look-up in the map to get the appropriate SessionFactory. This is a perfect fit for the command pattern....we do a very similar thing on my projects and it works great.

-Matt