Data Access Layer Design

Hi,

I need to create a Data access layer for my application. This is what i have in my mind.

A class called SqlDataProvider.cs or OracleDataProvider.cs this class will have the necessary functions for DB communication. (ExectureReader, ExecteDataset etc)

in the same level another class Called MyAppDataProvider.cs which derives the above Data provider. and this this class will not  have any functions implemented in  it. its just a derived class. Then, in the same level I will be having the relevant categorized classes like UserManagementDataProvider.cs which will derive the MyAppDataProvider.cs class. So, my business layer always creates a instant of UserManagementDataProvider class to communicate to DB. is this way is correct..? can u suggest me an another efficient way with some sample please. I feel deriving classes makes the object more weight.