How to change the database instance for web service which uses entity beans

Hello,

I have created a web service which uses entity beans. I will have a config file for the web service. One of the properties is the database url. My question is how can I change the database programically? I want to be able to read the config file and make the change. I think I would have to change the dbschema file to point to the new database, (changing the jar file), and then redeploy, but this can't be done programically. Is this the only way?

Thank you.

Ravi