.NET C# DropDownList içine SQL Server'dan Parametreli Veri Çekmek

      if (!IsPostBack)
        {
            DropDownList1.Items.Clear();
            SqlCommand merk = new SqlCommand("SELECT  Alanad AS AD FROM TabloAd where Con1='" + param1+ "' ORDER BY AD", serkan);
            SqlDataReader objDataReader = null;
            serkan.Open();
            DropDownList1.Items.Add("xxx Tipi Seçiniz");
            objDataReader = merk.ExecuteReader();
            while (objDataReader.Read() == true)
            {
                DropDownList1.Items.Add(objDataReader["AD"].ToString());
            }
            objDataReader.Close();
            serkan.Close();
        }