Retrieve pdf from sqlserver in asp.net and C#.net

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;

public partial class image : System.Web.UI.Page
{
    SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["NewJapConnectionString"].ToString());

    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void GridView2_SelectedIndexChanged(object sender, EventArgs e)
    {
        //using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["NewJapConnectionString"].ToString())) 

        con.Open();
        SqlCommand cmd = new SqlCommand("select ImageName,Extension,Image from Images where R_No=@R_No", con);
        cmd.Parameters.AddWithValue("R_No", GridView2.SelectedRow.Cells[1].Text);
        SqlDataReader dr = cmd.ExecuteReader();

        if (dr.Read())
        {
            Response.Clear();
            Response.Buffer = true;

            Response.ContentType = dr["Extension"].ToString();
            Response.AddHeader("content-disposition", "attachment;filename=" + dr["ImageName"].ToString());
            Response.Charset = "";
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            Response.BinaryWrite((byte[])dr["Image"]);

            Response.End();

        }
       
    }
}

<%@ Page Language="C#" MasterPageFile="~/VC_Master.master" AutoEventWireup="true" CodeFile="image.aspx.cs" Inherits="image" Title="Untitled Page" %>

<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:GridView ID="GridView2" runat="server" AutoGenerateColumns="False"  
    DataKeyNames="R_No" DataSourceID="SqlDataSource1"  
    onselectedindexchanged="GridView2_SelectedIndexChanged" Width="339px"> 
    <columns> 
        <asp:CommandField ShowSelectButton="True"  
            SelectText="Download" ButtonType="Button"  SelectImageUrl="Handler.ashx" /> 
        <asp:BoundField DataField="R_No" HeaderText="ID" InsertVisible="False"  
            ReadOnly="True" SortExpression="ID" /> 
        <asp:BoundField DataField="ImageName" HeaderText="FileName"  
            SortExpression="FileName" />
            
    </columns> 
 
<asp:SqlDataSource ID="SqlDataSource1" runat="server"  
    ConnectionString="<%$ ConnectionStrings:NewJapConnectionString %>"  
    DeleteCommand="delete from Images where R_No=@R_No"  
    SelectCommand="select R_No, ImageName from Images"  
     
    InsertCommand="insert into Images (ImageName,Extension,Image) values (@ImageName,@Extension,@Image)"> 
    <deleteparameters> 
        <asp:ControlParameter ControlID="GridView2" Name="R_No"  
            PropertyName="SelectedValue" /> 
    </deleteparameters>