Pro C# 2010 and the .NET 4 Platform, Fifth Edition

21.5. Abstracting Data Providers Using Interfaces

At this point, you should have a better idea of the common functionality found among all .NET data providers. Recall that even though the exact names of the implementing types will differ among data providers, you can program against these types in a similar manner—that's the beauty of interface-based polymorphism. For example, if you define a method that takes an IDbConnection parameter, you can pass in any ADO.NET connection object:

public static void OpenConnection(IDbConnection cn)
{
  // Open the incoming connection for the caller.
  cn.Open();
}

NOTE

Interfaces are not strictly required; you can achieve the same level of abstraction using abstract base classes (such as DbConnection) as parameters ...