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
STEP 1: Setting up the Connection string
In your webconfig file set up the connection string there as shown below:
<connectionStrings>
<add name="DBConnection" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Northwind.mdf;Integrated Security=True;User Instance=True" providerName="System.Data.SqlClient"/>
</connectionStrings>
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="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Binding DropDownList</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:DropDownList ID="DropDownList1" runat="server">
</asp:DropDownList>
</div>
</form>
</body>
</html>
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)
{
BindDropDownList();
}
}
private string GetConnectionString()
{
return System.Configuration.ConfigurationManager.ConnectionStrings["DBConnection"].ConnectionString;
}
private void BindDropDownList()
{
DataTable dt = new DataTable();
SqlConnection connection = new SqlConnection(GetConnectionString());
try
{
connection.Open();
string sqlStatement = "SELECT Top(20)* FROM Customers";
SqlCommand sqlCmd = new SqlCommand(sqlStatement, connection);
SqlDataAdapter sqlDa = new SqlDataAdapter(sqlCmd);
sqlDa.Fill(dt);
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
DropDownList1.DataBind();
}
}
catch (System.Data.SqlClient.SqlException ex)
{
string msg = "Fetch Error:";
msg += ex.Message;
throw new Exception(msg);
}
finally
{
connection.Close();
}
}
}
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