Can you please tell me where NopCommerce.DataAccess has moved to?

I have upgraded a 1.6 site to 1.9 which had some custom functions which used built in functionality from  NopCommerce.DataAccess

However this project will not compile - I get 116 errors referencing NopSolutions.NopCommerce.DataAccess; which is not found.

Has this built in functionality been removed in 1.9?
or has it just moved? If it has moved what should I change the references to?


I look forward to your reply.