Specify database with a parameter.

We have several databases that are identical except for the name and physical data.  [tables/views etc are all the same]

I want to write a report that the user can select the database with a parameter (or other method), something like:

use @carrier 
select top(2) invNumber from invoices

or

select top(2) invNumber from @carrier.dbo.invoices

Where @carrier would contain the name of the database.  [carrierX, carrierY etc]

I know the above won't work, but is there any way to accomplish the same concept?