confirmation box using gridview control when delete button click

under.aspx
-----------

  <asp:GridView DataKeyNames="sno" ID="GridView1"
       runat="server" AutoGenerateColumns="False"
       OnRowCommand="GridView1_RowCommand"
       OnRowDataBound="GridView1_RowDataBound"
       OnRowDeleted="GridView1_RowDeleted" OnRowDeleting="GridView1_RowDeleting">
  <Columns>
   <asp:BoundField DataField="sno" HeaderText="sno" />
   <asp:BoundField DataField="name" HeaderText="name" />
   <asp:TemplateField HeaderText="Select">
     <ItemTemplate>
       <asp:LinkButton ID="LinkButton1"
         CommandArgument='<%# Eval("sno") %>'
         CommandName="Delete" runat="server">
         Delete</asp:LinkButton>
     </ItemTemplate>
   </asp:TemplateField>
  </Columns>
</asp:GridView>



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;
using System.Configuration;

public partial class dummy : System.Web.UI.Page
{

    SqlConnection con = null;
    SqlCommand cmd = null;
    SqlDataReader dr = null;
    protected void Page_Load(object sender, EventArgs e)
    {
        con = new SqlConnection(ConfigurationManager.ConnectionStrings["connection"].ConnectionString);
        con.Open();
        cmd = new SqlCommand("select sno,name from dummy",con);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataSet ds = new DataSet();
        da.Fill(ds);
        GridView1.DataSource = ds;
        GridView1.DataBind();
        con.Close();

    }
 
  

    protected void GridView1_RowDataBound(object sender,
                          GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            LinkButton l = (LinkButton)e.Row.FindControl("LinkButton1");
            l.Attributes.Add("onclick", "javascript:return " +
            "confirm('Are you sure you want to delete this record " +
            DataBinder.Eval(e.Row.DataItem, "sno") + "')");
        }
    }


    protected void GridView1_RowCommand(object sender,
                         GridViewCommandEventArgs e)
    {
        if (e.CommandName == "Delete")
        {
            // get the categoryID of the clicked row

            int sno = Convert.ToInt32(e.CommandArgument);
            // Delete the record

           // DeleteRecordByID(categoryID);
            con.Open();
            cmd = new SqlCommand("delete from dummy where sno=@sno", con);
            cmd.Parameters.Add(new SqlParameter("@sno", sno));
            cmd.ExecuteNonQuery();
            con.Close();


            // Implement this on your own :)

        }
    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        int sno = (int)GridView1.DataKeys[e.RowIndex].Value;
       // DeleteRecordByID(categoryID);
        con.Open();
        cmd = new SqlCommand("delete from dummy where sno=@sno",con);
        cmd.Parameters.Add(new SqlParameter("@sno",sno));
        cmd.ExecuteNonQuery();
        con.Close();
    }


    protected void GridView1_RowDeleted(object sender, GridViewDeletedEventArgs e)
    {

    }
}