Overview of ADO.NET Classes and Objects

The diagram in Figure 24-1 shows the basic classes in ADO.NET. Note that this is not an inheritance diagram but rather shows the relationships between the most commonly used classes.

Figure 24-1

Here the classes are divided into .NET data provider objects and consumer objects.

• Provider objects are specific to each type of data source — the actual reading and writing to and from the data source is done with the provider-specific objects.
• Consumer objects are what you use to access and manipulate the data once you have read it into memory.

The provider objects require an active connection. You use these first to read the data, then depending on your needs, you may work with the data in memory using the consumer objects. You can also update the data in the data source using the provider objects to write the changes back to the data source. Thus, the consumer objects operate in a disconnected fashion; you can work with the data in memory even if the database connection is down.