public List <DocGia> getAll(string Top, string Where, string Order)
        {
            List <DocGia> lst         = new List <DocGia>();
            string        selectQuery = "select ";

            if (Top.Length != 0)
            {
                selectQuery += "Top " + Top;
            }
            selectQuery += "* ";
            selectQuery += "from tb_DocGia ";
            if (Where.Length != 0)
            {
                selectQuery += "Where " + Where;
            }
            if (Order.Length != 0)
            {
                selectQuery += "Order by " + Order;
            }

            using (SqlCommand cmd = new SqlCommand(selectQuery, openConnection()))
            {
                SqlDataReader dr;
                dr = cmd.ExecuteReader();
                while (dr.Read())
                {
                    DocGia obj = new DocGia();
                    obj.DocGiaIDataReader(dr);
                    lst.Add(obj);
                }
                dr.Close();
            }
            return(lst);
        }