ABAP 动态内表如何分组循环

  LOOP AT <fs_dytable> ASSIGNING <fs_dywa> GROUP BY SWITCH string( lv_flag WHEN 'A' THEN |MATNR = <FS_DYWA>-MATNR|
                                                                            WHEN 'B' THEN |MATNR = <FS_DYWA>-MATNR WERKS = <FS_DYWA>-WERKS STLAN = <FS_DYWA>-STLAN STLAL = <FS_DYWA>-STLAL| )
                              ASCENDING ASSIGNING FIELD-SYMBOL(<group>).
    LOOP AT GROUP <group> ASSIGNING FIELD-SYMBOL(<fs>).
      MOVE-CORRESPONDING <fs> TO gs_handle.
    ENDLOOP.

  ENDLOOP.

动态内表如何分组循环，group by 里面的-matnr在运行时，没有被assigning,所以条件并没有起作用，有什么办法可以让动态内表分组循环

  LOOP AT <fs_dytable> ASSIGNING <fs_dywa>.
    ASSIGN COMPONENT 'MATNR' OF STRUCTURE <fs_dywa> TO FIELD-SYMBOL(<fs_matnr>).
    ASSIGN COMPONENT 'STLAL' OF STRUCTURE <fs_dywa> TO FIELD-SYMBOL(<fs_stlal>).
    AT END OF <fs_stlal>.
       lv_flag = 'B'.
    ENDAT.
  ENDLOOP.

我真傻，真的，没想到这么简单，没想到这样也可以