MSDN Documentation

ADO.NET Data Providers

ADO.NET data providers are fundamental components that enable ADO.NET applications to access data from a variety of data sources. Each data provider implements a common set of interfaces defined by ADO.NET, ensuring a consistent programming model regardless of the underlying data store.

Understanding the Data Provider Model

The ADO.NET data provider model is designed for extensibility. It abstracts the details of data source interaction, allowing developers to work with data in a uniform way. The core components of a data provider include:

• Connection objects: Establish a connection to the data source.
• Command objects: Execute SQL statements or stored procedures.
• DataReader objects: Provide a forward-only, read-only stream of data from the data source.
• DataAdapter objects: Facilitate the filling of a DataSet with data from a data source and resolving updates to the data source based on changes made to the DataSet.
• DataSet objects: Represent an in-memory cache of data retrieved from a data source.

Key Data Providers

Microsoft provides several built-in data providers, each tailored for specific data sources. Some of the most common include:

• .NET Data Provider for SQL Server: Optimized for Microsoft SQL Server.
• .NET Data Provider for OLE DB: Allows access to any OLE DB compliant data source.
• .NET Data Provider for ODBC: Enables interaction with data sources through ODBC drivers.

Third-party vendors also offer data providers for other databases such as Oracle, MySQL, PostgreSQL, and more.

Using a Data Provider

The general workflow for using a data provider involves the following steps:

1. Instantiate the appropriate DbConnection object (e.g., SqlConnection, OleDbConnection).
2. Open the connection to the data source.
3. Instantiate the appropriate DbCommand object (e.g., SqlCommand, OleDbCommand) and associate it with the connection.
4. Execute the command. This can be done to retrieve data (using ExecuteReader, ExecuteScalar, or ExecuteNonQuery) or to perform data modification operations.
5. If data is retrieved, process the results using a DataReader or populate a DataSet using a DataAdapter.
6. Close the connection when finished.

using System.Data.SqlClient;

// ...

string connectionString = "Server=myServerAddress;Database=myDataBase;User ID=myUsername;Password=myPassword;";

using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    string sql = "SELECT TOP 5 CustomerID, CompanyName FROM Customers;";
    using (SqlCommand command = new SqlCommand(sql, connection))
    {
        using (SqlDataReader reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                Console.WriteLine($"ID: {reader["CustomerID"]}, Name: {reader["CompanyName"]}");
            }
        }
    }
}

                

Abstract Base Classes

ADO.NET also defines abstract base classes (e.g., DbConnection, DbCommand, DbDataReader, DbDataAdapter) in the System.Data.Common namespace. These classes provide a common interface and implementation details that specific data providers can inherit from, further promoting code reusability and consistency.

By abstracting the data access layer, ADO.NET data providers allow applications to be more flexible and adaptable to different data storage solutions without significant code refactoring.