Licensing: Can You Use Copylefted Materials Without Sharing Your Derivative Work

Hi everyone,
We are working on a website at our company and want to use a database that is licensed under the Open Data Commons Open Database License. It say "you may alter or build upon this data, you may distribute the result only under the same license."

Now we need to add more metadata to each data point in this database for our web application to work.

My questions is do we have to release our added meta data under the same license or can we keep it under a private company license?

Thanks in advance,
Jane

Licensing: Can You Use Copylefted Materials Without Sharing Your Derivative Work