Programming C#, Second Edition

Using OLE DB Managed Providers

The previous example used one of the two managed providers currently available with ADO.NET: the SQL Server Managed Provider and OLE DB Managed Provider. The SQL Server Managed Provider is optimized for SQL Server and is restricted to working with SQL Server databases. The more general solution is the OLE DB Managed Provider, which will connect to any OLE DB provider, including Access.

You can rewrite Example 14-1 to work with the Northwind database using Access rather than SQL Server with just a few small changes. First, you need to change the connection string:

string connectionString = 
    "provider=Microsoft.JET.OLEDB.4.0; "
    + "data source = c:\\nwind.mdb";

This query connects to the Northwind database on C drive. (Your exact path might be different.)

Next, change the DataAdapter object to an ADODataAdapter rather than a SqlDataAdapter:

OleDbDataAdapter DataAdapter = 
    new OleDbDataAdapter (commandString, connectionString);

Also be sure to add a using statement for the OleDb namespace:

using System.Data.OleDb;

This design pattern continues throughout the two Managed Providers; for every object whose class name begins with “Sql,” there is a corresponding class beginning with “OleDb.” Example 14-2 illustrates the complete OLE DB version of Example 14-1.

Example 14-2. Using the ADO Managed Provider

using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Data.OleDb; ...