private DataTable load_data_from_tu_dien(decimal id_loai_tu_dien)
{
US_CM_DM_TU_DIEN v_us = new US_CM_DM_TU_DIEN();
DS_CM_DM_TU_DIEN v_ds = new DS_CM_DM_TU_DIEN();
v_us.FillDataset(v_ds, "WHERE ID_LOAI_TU_DIEN = " + id_loai_tu_dien);
return v_ds.Tables[0];
}