Look into DB Unit. It is a Java library, but there must be a C# equivalent. It lets you prepare the database with a set of data so that you know what is in the database, then you can interface with DB Unit to see what is in the database. It can run against many database systems, so you can use your actual database setup, or use something else, like HSQL in Java (a Java database implementation with an in memory option).
If you want to test that your code is using the database properly (which you most likely should be doing), then this is the way to go to isolate each test and ensure the database has expected data prepared.