/// <summary>
        /// The method that supports editing the adverts created.
        /// It retrieves data from the form by the user, then calls the EditAnnouncement method,
        /// sending these values as method parameters.
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Edit_Announcement(object sender, EventArgs e)
        {
            db = new SQLDatabase();
            db.Connect();
            int id_a;

            if (Request.QueryString["id_a"] != null)
            {
                id_a = int.Parse(Request.QueryString["id_a"]);
                db.EditAnnouncement(id_a, end_date.Value, one.Checked, subject.Value, content.Value);
            }
            Response.Redirect("MyActivities.aspx");
            db.Disconnect();
        }