*low efficiency

   l_it_alv_stpox[] = g_it_alv_stpox[].

  SORT l_it_alv_stpox BY zz_matnr idnrk.

  LOOP AT g_it_alv_stpox ASSIGNING <l_wa_alv>.

    LOOP AT l_it_alv_stpox WHERE ( zz_matnr NE <l_wa_alv>-zz_matnr )

                             AND ( idnrk EQ <l_wa_alv>-idnrk )

                             AND ( zz_bunit IS NOT INITIAL )

                             AND ( zz_bunit NE <l_wa_alv>-zz_bunit ).

      <l_wa_alv>-zz_bunit = 'Common'.

      EXIT.

    ENDLOOP.

    UPDATE marc SET zz_bunit = <l_wa_alv>-zz_bunit WHERE werks = <l_wa_alv>-werks

                                                     AND matnr = <l_wa_alv>-idnrk                                                    .

    IF sy-subrc EQ 0.

      COMMIT WORK.

      <l_wa_alv>-zz_message  = l_message_s.

    ELSE.

      ROLLBACK WORK.

      <l_wa_alv>-zz_message  = l_message_f.

    ENDIF.

  ENDLOOP.

***大内表LOOP嵌套LOOP，速度太慢，转化成以下逻辑 ***

 delete adjacent duplicates from g_it_alv_stpox comparing zz_matnr idnrk.

  l_it_idnrk_stpox[] = g_it_alv_stpox[].

  sort l_it_idnrk_stpox by idnrk.

  delete adjacent duplicates from l_it_idnrk_stpox comparing idnrk.

   l_it_both_stpox[] = l_it_idnrk_stpox[].

  loop at l_it_idnrk_stpox into l_wa_idnrk_stpox.

    l_it_stpox_in_loop[] = l_it_both_stpox[].

    delete l_it_stpox_in_loop where idnrk ne l_wa_idnrk_stpox-idnrk.

    delete l_it_both_stpox where idnrk eq l_wa_idnrk_stpox-idnrk.

    describe table l_it_stpox_in_loop lines l_lines.

    if l_lines gt 1.

      l_wa_idnrk_stpox-zz_bunit = 'Common'.

    endif.

    clear l_lines.

    update marc set zz_bunit = l_wa_idnrk_stpox-zz_bunit where werks = l_wa_idnrk_stpox-werks

                                                     and matnr = l_wa_idnrk_stpox-idnrk.

    if sy-subrc eq 0.

      commit work.

      l_wa_idnrk_stpox-zz_message  = l_message_s.

    else.

      rollback work.

      l_wa_idnrk_stpox-zz_message  = l_message_f.

    endif.

    modify g_it_alv_stpox from l_wa_idnrk_stpox transporting zz_bunit zz_message

    where werks = l_wa_idnrk_stpox-werks and idnrk = l_wa_idnrk_stpox-idnrk.

  endloop.

  clear:l_wa_idnrk_stpox.

***上面一段有误，改成以下 ***

sort lt_stpox by idnrk zz_bunit.

    delete adjacent duplicates from lt_stpox comparing idnrk zz_bunit.

    describe table lt_stpox lines l_lines.

  endif.

*  PERFORM frm_check_users.

  write: 'LT_STPOX lines:' , l_lines.

  lt_mara[] = lt_stpox[].

  sort: lt_mara by idnrk.

  delete adjacent duplicates from lt_mara comparing idnrk .

  sort:  lt_stpox  by idnrk.

  describe table lt_mara lines l_lines.

  write: 'LT_MARA:' , l_lines.

  loop at lt_mara into ls_mara.

    l_maraindex = sy-tabix.

    read table lt_stpox into ls_stpox with key idnrk = ls_mara-idnrk binary search.

    if sy-subrc = 0.

      l_index = sy-tabix.

      loop at lt_stpox into ls_stpox from l_index.

        if ls_stpox-idnrk ne ls_mara-idnrk.

          exit.

        endif.

        if ls_stpox-zz_bunit ne ls_mara-zz_bunit.

          ls_mara-zz_bunit = 'Common'.

          exit.

        endif.

      endloop.

      update marc set zz_bunit = ls_mara-zz_bunit where werks = p_werks

                                                         and matnr = ls_mara-idnrk.

      if sy-subrc eq 0.

        commit work.

      else.

        rollback work.

      endif.

      write: /.

      write:l_maraindex, ls_mara-idnrk, ls_mara-zz_bunit.

    endif.

  endloop.