Need Help in Database Design

Hi Experts,

I am indulged in developing Online Issue Tracking sytem.For that I have met with a problem in Database creation.

The Sceneario is "The Database should be specific for each and every group of customers,For example initially A is a company with 10 users accessing the product after two days B is a company with 50 user accessing the same product".In this case the datase base should be provided to the two companies separately to maintain their transaction. How to handle this.

Any sort of ideas is valuable for me.
Thanks,
Ramanan