store the number of button clicks asp.net (c#)

Question

I have given the user the option to download images that are being uploaded by a provider. When the download button is clicked the image downloads. But I also want to store how many times that download button is clicked. For that I typed this code, but it isn't working.

I tried several ways like declaring an int variable and increment it. Didn't work. Then I tried this. Still not working. What am I doing wrong?

 protected void btn_download_Click(object sender, EventArgs e)
        {


            var res = (byte[])Session["Image"];

           Response.Clear();
            MemoryStream ms = new MemoryStream(res);
            Response.ContentType = "image/jpeg";
            Response.AddHeader("content-disposition", "attachment;filename=Image.jpg");
            Response.Buffer = true;
            ms.WriteTo(Response.OutputStream);
            Response.End();



            try
            {

                SqlCommand command = new SqlCommand("UPDATE [ImageWithTags] SET DownloadCount = DownloadCount + 1 WHERE ImageID='" + DropDownList1.SelectedItem.Text + "'", con);
                con.Open(); 
                command.ExecuteNonQuery();
                con.Close();
            }
            catch (Exception ex)
            {
                Response.Write(ex.Message);
            }




        }

Answer 1

You can create a session variable for that as well and do the calculations like:

protected void btn_download_Click(object sender, EventArgs e)
{
    int counter=0;    
    if(Session["counter"]!=null)
     {
        Session["counter"] = ++Convert.ToInt32(Session["counter"]);
        counter = Convert.ToInt32Session["counter"];
     }
    else
      Session["counter"] = 0;
        // do your calculation here with variable counter
}