Using the ADO Recordset in ADO.NET

Mahesh Chand
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This article has been excerpted from book "A Programmer's Guide to ADO.NET in C#".

Using Visual Studio .NET, you can import a type library in an application using the Project > Add Reference menu option. The Add Reference option adds the assembly namespace to your project.

In this sample, you'll see how to import the ADO type library and use the ADO recordset to access a database. After that, you'll fill data to a DataSet from the ADO recordset using a data adapter.

To test this application, create a Windows application and drag a DataGrid control to the form from the toolbox. To add a reference to a COM type library, go to the Add reference option from the project menu and select the COM tab in the Add Reference dialog box. As you can see from figure 10-24, I selected Microsoft ActiveX Data Objects 2.7 Library. Click select to add the selection to the selected components list. Now click OK.

Figure 10-24. Adding a reference to a COM library

This action adds the ADODB namespace to the project. You can see this namespace from the project namespace (see figure 10-25).

Figure 10-25. Namespace after adding ADODB namespace to the project

After adding a reference of a namespace to a project, its members are available for use in your project. You include this namespace in your application by calling using. You also should add a reference to the System.Data.OleDb namespace because you'll use the OleDb data adapter to fill a dataset. So, add these two namespace references to the project with this:

using System.Data.OleDb;

using ADODB;

Now you can use the ADO recordset and connection to access a database. As you can see from listing 10-6, I created a Connection object and set the connection mode and cursor location. After that I called the connectionn's Execute method to execute a SQL statement that returns the _Recordset object. The Fill method of data adapter reads data from a recordset and fills data to a dataset. As you can see, I also created a dataset and data adapter and called the data adapter's Fill method. The Fill method takes three parameters: a dataset, a recordset, and a dataset name. After that, bind the dataset to a data grid in order to fill data from the dataset to the data grid.

Listing 10-6. Using ADODB namespace to access a database

private void Form1_load(object sender, System.EventArgs e)

{

// Create SQL and Connection strings

string ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0; DataSource=C:/Northwind.mdb";

string sql = "SELECT CustomerID,CompanyName,ContactName From Customers";

// Create a Connection object and open it

Connection conn = new Connection();

int connMode = (int)ConnectModeEnum.adModeUnknown;

conn.CursorLocation = CursorLocationEnum.adUseServer;

conn.Open(ConnectionString, " ", " ", connMode);

object recAffected = null;

int cmdType = (int)CommandTypeEnum.adCmdText;

_Recordset rs = conn.Execute(sql, out recAffected, cmdType);

// Create dataset and data adapter objects

DataSet ds = new DataSet("Recordset");

OleDbDataAdapter da = new OleDbDataAdapter();

// Call data adapter's Fill method to fill data from ADO

// Recordset to the dataset

da.Fill(ds, rs, "Customers");

// Now use dataset

dataGrid1.DataSource = ds.DefaultViewManager;

}

The output of listing 10-6 looks like figure 10-26.

Figure 10-26. Displaying data from an ADO recordset to a data grid

Conclusion

Hope this article would have helped you in understanding Hypertext Markup Language (HTML), XML, and other Web-related technologies. See other articles on the website also for further reference.

This essential guide to Microsoft's ADO.NET overviews C#, then leads you toward deeper understanding of ADO.NET.

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