Simple way to fetch data from database into dropdownlist Asp.NET

First Create a Table 

Then Save it.
Then add data into table

Drag dropdownlist control from toolbox in default.aspx file :-

<asp:DropDownList ID="DropDownList1" runat="server">

        </asp:DropDownList>

Now write the following code in Default.aspx.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Data;

using System.Data.SqlClient;

public partial class _Default : System.Web.UI.Page

{

    SqlConnection cn;

    SqlCommand cmd;

    SqlDataAdapter da;

    protected void Page_Load(object sender, EventArgs e)

    {

        cn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=E:\C#\WebSites\DropDownList DataBase 4\App_Data\Database.mdf;Integrated Security=True;User Instance=True");

        cmd = new SqlCommand("Select * from Mahi", cn);

        da = new SqlDataAdapter(cmd);

        DataSet ds = new DataSet();

        da.Fill(ds);

        DropDownList1.DataSource = ds;

        DropDownList1.DataTextField = "Name";

        DropDownList1.DataValueField = "ID";

        DropDownList1.DataBind();

    }

}