Why is there no Oracle base type?

Question

I would like to know why ODP.NET Oracle types such as OracleDecimal, OracleString, OracleBlob, etc have no common base type or interface. There are some methods and properties that more than obviously are suited to being in such an interface (or base class). Specifically for me these are "bool IsNull { get; }" and "public string Value { get; }". Why should I even have to know the Oracle type when I get the .NET type from it?

Answer 1

Sorry, skj, I didn't see your post until now. For some reason, I only got a notification after Eric's post.
Yes, I am talking about out parameters. If you read out these and want to test for null, testing equality with DBNull.Value doesn't work. You have to cast to the Oracle type in question, e.g. OracleDecimal, and use the IsNull property defined there.
I wrote the following null checking method using reflection, but I don't think this is a very elegant way to solve the problem:
public static bool IsNull(object o)
     if (o == null || o == DBNull.Value)
          return true;
     PropertyInfo propertyInfo = o.GetType().GetProperty("IsNull");
     if (propertyInfo == null)
          return false;
     MethodInfo methodInfo = propertyInfo.GetGetMethod();
     return (bool)methodInfo.Invoke(o, null);
}