protected void Page_Load(object sender, EventArgs e)
 {
     if (!IsPostBack)
     {
         drpDate.DataSource     = DateInstance.getListDate();
         drpDate.DataValueField = "DateValue";
         drpDate.DataTextField  = "Name";
         drpDate.DataBind();
     }
 }
        protected void drpDate_SelectedIndexChanged(object sender, EventArgs e)
        {
            DateInstance [] data2        = DateInstance.getListDate().ToArray();
            DateInstance    dateInstance = null;

            for (int i = 0; i < data2.Length; i++)
            {
                if (i == drpDate.SelectedIndex)
                {
                    dateInstance = data2[i];
                    break;
                }
            }

            if (dateInstance == null)
            {
                dateInstance = new DateInstance(1, "Hôm nay", DateTime.Now);
            }

            if (HttpContext.Current.Session["dateg"] != null)
            {
                HttpContext.Current.Session["dateg"] = dateInstance;
            }
        }