The ADO.NET class hierarchy can be split into two categories: connected and disconnected objects. Figure 1-1 shows the principal connected and disconnected classes. This chapter describes the disconnected classes that are shown in the diagram and many other classes of this category as well. I cover the disconnected classes in detail because these classes can be used without your ever creating a connection to a data store. In Chapter 2, I'll discuss the connected classes in detail.
Figure 1-1: The more familiar disconnected and connected classes
The classes shown in Figure 1-1 existed in previous versions of ADO.NET, but these are the primary ADO.NET classes, so knowing them well is important if you want to successfully implement an ADO.NET solution. In ADO.NET 2.0, the primary classes have additional methods and properties to improve functionality and performance of your code.
The disconnected data access classes are instantiated within the client application and (as I said earlier) can be used without ever connecting to a data store. Because you must use the DataTable object when you're using disconnected classes, this chapter begins by covering it and the objects that the DataTable object works with closely. Next I'll discuss the DataSet object in detail. Finally I'll describe the DataTableReader object, an ADO.NET object that is new in version 2.0.