ADO.NET Architecture

ADO.NET Components

The two main components of ADO.NET 3.0 for accessing and manipulating data are the .NET Framework data providers and the DataSet.

.NET Framework Data Providers

The .NET Framework Data Providers are components that have been explicitly designed for data manipulation and fast, forward-only, read-only access to data. The Connectionobject provides connectivity to a data source. The Command object enables access to database commands to return data, modify data, run stored procedures, and send or retrieve parameter information. The DataReader provides a high-performance stream of data from the data source. Finally, the DataAdapter provides the bridge between theDataSet object and the data source. The DataAdapter uses Command objects to execute SQL commands at the data source to both load the DataSet with data and reconcile changes that were made to the data in the DataSet back to the data source. For more information, see .NET Framework Data Providers (ADO.NET) and Retrieving and Modifying Data in ADO.NET.

The DataSet

The ADO.NET DataSet is explicitly designed for data access independent of any data source. As a result, it can be used with multiple and differing data sources, used with XML data, or used to manage data local to the application. The DataSet contains a collection of one or more DataTable objects consisting of rows and columns of data, and also primary key, foreign key, constraint, and relation information about the data in the DataTable objects. For more information, see DataSets, DataTables, and DataViews (ADO.NET).
The following diagram illustrates the relationship between a .NET Framework data provider and a DataSet.

ADO.NET architecture

Choosing a DataReader or a DataSet

When you decide whether your application should use a DataReader (see Retrieving Data Using a DataReader (ADO.NET)) or a DataSet (see DataSets, DataTables, and DataViews (ADO.NET)), consider the type of functionality that your application requires. Use a DataSet to do the following:

• Cache data locally in your application so that you can manipulate it. If you only need to read the results of a query, the DataReader is the better choice.
• Remote data between tiers or from an XML Web service.
• Interact with data dynamically such as binding to a Windows Forms control or combining and relating data from multiple sources.
• Perform extensive processing on data without requiring an open connection to the data source, which frees the connection to be used by other clients.

If you do not require the functionality provided by the DataSet, you can improve the performance of your application by using the DataReader to return your data in a forward-only, read-only manner. Although the DataAdapter uses the DataReader to fill the contents of a DataSet (see Populating a DataSet from a DataAdapter (ADO.NET)), by using the DataReader, you can boost performance because you will save memory that would be consumed by the DataSet, and avoid the processing that is required to create and fill the contents of the DataSet.