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Wednesday, October 13, 2010

Binding DropDownList Control the ADO.NET way.

Note that in this demo, I’m using the Northwind database. Now let’s set up the connection string.

STEP 1: Setting up the Connection string
In your webconfig file set up the connection string there as shown below:
    <add name="DBConnection" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Northwind.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>

Note: DBConnection is the name of the Connection String that we can use as a reference in our codes.

In code behind, you can reference that connection string like this:

private string GetConnectionString()
   return System.Configuration.ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;

Since we are done setting up the connection string then we can start populating the Controls, first let’s start populating the DropDownList.

STEP 2: Populating the DropDownList

To start, grab a DropDownList control from the visual studio ToolBox and place it the WebForm. The ASPX source should look something like this:

<html xmlns="" >
<head runat="server">
    <title>Binding DropDownList</title>
    <form id="form1" runat="server">
        <asp:DropDownList ID="DropDownList1" runat="server">

 Here’s the code block for binding the DropDownList in the code behind:

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;
using System.Collections.Specialized;
using System.Text;

public partial class _Default : System.Web.UI.Page
    protected void Page_Load(object sender, EventArgs e)
        if (!IsPostBack)

    private string GetConnectionString()
        return System.Configuration.ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;

    private void BindDropDownList()
        DataTable dt = new DataTable();
        SqlConnection connection = new SqlConnection(GetConnectionString());
            string sqlStatement = "SELECT Top(20)* FROM Customers";
            SqlCommand sqlCmd = new SqlCommand(sqlStatement, connection);
            SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);

            if (dt.Rows.Count > 0)
                DropDownList1.DataSource =dt;
                DropDownList1.DataTextField = "ContactName"; // the items to be displayed in the list items
                DropDownList1.DataValueField = "CustomerID"; // the id of the items displayed
        catch (System.Data.SqlClient.SqlException ex)
            string msg = "Fetch Error:";
            msg += ex.Message;
            throw new Exception(msg);

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