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ADO.NET

ADO.NET is the data access model that comes with the .NET Framework. ADO.NET provides the classes required to communicate with any database source (including Oracle, Sybase, Microsoft Access, Xml, and even text files).

DataAccess Providers in .NET

ADO.NET comes with few providers, including:

OleDb

SqlClient

There are other providers available, but we are not including them here as this tutorial is meant for beginners! When you want them, search for ADO.NET providers in Google or MSDN

Microsoft made the SQL Server. So they gave a separate provider, specifically made for SQL Server. We can use the OleDb provider for all other database sources including MS Access, Oracle, Sybase etc. There is a separate provider available for Oracle.

A DATA PROVIDER is a set of classes that can be used to access, retrieve and manipulate data from the databases.

Both OleDb and SqlClient has its own set of classes, but they have the same concepts. We would like to classify the classes into two broad categories (this is not a microsoft classification, anyway!)

Classes for communicate with database

Classes for holding/manipulating data

The job of first category of classes is to communicate with database and send or retrieve data from the database. The second category of the classes will be used as a carrier of data.

Classes for communicating with database

The Connection, Command, DataReader, and DataAdapter
objects are the core elements of the ADO.NET provider model.

Each provider may have classes equivalent to above objects. The name of the classes vary slightly to represent the provider type appropriately.

Depending on the type of database you work on, you will have to choose either OleDb or SqlClient (or, some other provider) objects. Since all our samples use MS Access database, we will be using OleDb objects in all the samples. If you like to use SqlServer, you just need to replace the OleDb objects with the equivalent SqlClient objects.

Classes for holding data

The following are the main classes used to hold data in Ado.NET:

DataSet

DataTable

DataRow

A DataSet is an in-memory representation of the database.

DataSet contains DataTables (and more...)

DataTable represents a database table

DataTable contains DataRows (and more...)

A DataRow represents a record in a database table.

DataRow is a collection of all fields in a record.

We can use the DataAdapter or DataReader to populate data in DataSet. Once we populate data from database, we can loop through all Tables in the DataSet and through each record in each Table.

On the first look, this may look bit confusing, but once you understand the concept and get familiar with the Ado.NET classes, you will appreciate the power and flexibility of Ado.NET.


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