As you can see by this diagram the class consists of 6 functions with 4 being public and 2 being private.
The 4 public functions match up to the same functions in the Business Layer. The Fetch, FetchList, Save and Search functions in the Business Layer are simple calls to these functions, which in turn are nothing more then SQL wrappers to the underlying database. The exception is the Save function. It has no direct access to the database, instead it simply checks for the ID property/value and redirects the call to either the Insert or Update functions as needed. This allows you to, if you felt so inclined, to add extra code/checks/whatever you wanted, and only on a particular function.
The DataBase is, as mentioned, a Microsoft SQLExpress database but you could easily change this with nearly any database out there or even switch it out to use XML if you wanted. As long as you leave the method names the same, and the return types, the other layers of the application would never even need to know. For the sake of documentation I've included the diagram of the two database table.
