ADO.NET is a set of .NET classes that allows retrieving, manipulating, and updating data from various sources. It consists of two main components - the dataset, which stores disconnected data, and data providers that connect to data sources using connections, commands, data readers, and data adapters. Data providers exist for SQL Server, OLE DB, and ODBC sources and each consists of classes to connect, execute commands, populate datasets, and update data sources.

1. Overview of ADO.NET
Architecture of ADO.NET
.NET Data Providers
Data Providers Components

2.  ADO.NET is a large set of .NET classes that
enable us to retrieve and manipulate data, and
update data.
 As an integral part of the .NET framework, it
shares many of its features:
 sources, in very many different ways.

3.  features such as multi-language support,
garbage collection, just-in-time compilation,
object-oriented design,
 and dynamic caching, and is far more than an
upgrade of previous versions of ADO.

4.  The ADO.NET object model consists of two
fundamental components: the Dataset, which
is disconnected from the data source and
doesn't need to know where the data it holds
came from; and the .NET
 data provider. The .NET data providers allow
us to connect to the data source, and to
execute SQL.

5.  At the time of writing, there are three .NET
data providers available: for SQL Server, for
OLE DB data sources.
 for ODBC-compliant data sources. Each
provider exists in a namespace within the
System. Data namespace, and
 consists of a number of classes.

6.  Each .NET data provider consists of four main
components:
 Connection – used to connect to the data
source
 Command– used to execute a command
against the data source and retrieve a Data
Reader.

7.  Dataset, or to execute an INSERT, UPDATE, or
DELETE command against the data source
 Data Reader– a forward-only, read-only
connected result set.
 Data Adapter – used to populate a Dataset
with data from the data source, and to update
the data source

9.  The connection classes are very similar to the
ADO Connection object, and like that, they are
used to
 represent a connection to a specific data source.
The connection classes store the information
that ADO.NET
 needs to connect to a data source in the form of
a familiar connection string (just as in ADO).

10.  The command classes expose the
IDbCommand interface and are similar to the
ADO Command object – they
 are used to execute SQL statements or stored
procedures in the data source. Also, like the
ADO Command
 object, the command classes have a Command
Text property, which contains the text of the
command to be

11.  executed against the data source, and a
Command Type property, which indicates
whether the command is a
 SQL statement, the name of a stored procedure,
or the name of a table.

13.  The DataReader is ADO.NET's answer to the
connected recordset in ADO. However, the
DataReader is
 forward-only and read-only – we can't navigate
through it at random, and we can't use it to
update the data source. It

14.  therefore allows extremely fast access to data
that we just want to iterate through once, and it
is recommended to use
 the Data Reader (rather than the DataSet)
wherever possible.

16.  The other major component of ADO.NET
is the DataSet; this corresponds very
roughly to the ADO
 recordset. It differs, however, in two
important respects. The first of these is
that the DataSet is always

17.  exactly the same way to manipulate data from
a traditional data source or from an XML
document. In order to
 connect a DataSet to a data source, we need to
use the DataAdapter as an intermediary
between the
 DataSet and the .NET data provider: