abap loop at GROUP BY

*&---------------------------------------------------------------------*
*& Report YABC_GROPUP_BY
*&---------------------------------------------------------------------*
*&
*&---------------------------------------------------------------------*
REPORT YABC_GROPUP_BY.

TYPES: BEGIN OF TY_ALV1.
TYPES: BUKRS TYPE BUKRS.
TYPES: VKORG TYPE VKORG.
TYPES: END OF TY_ALV1.

TYPES: BEGIN OF TY_ALV2.
TYPES: SELE TYPE C.
       INCLUDE TYPE TY_ALV1.
TYPES: END OF TY_ALV2.

TYPES: TYT_ALV1 TYPE STANDARD TABLE OF TY_ALV1 WITH DEFAULT KEY.
TYPES: TYT_ALV2 TYPE STANDARD TABLE OF TY_ALV2 WITH DEFAULT KEY.

DATA: GS_ALV2  TYPE TY_ALV2,
      GT_ALV2  TYPE TABLE OF TY_ALV2,
      GT_ALV2T TYPE TABLE OF TY_ALV2.

DATA: GT_ALV1T TYPE TABLE OF TY_ALV1.
DATA: GS_ALV1T TYPE TY_ALV1.

START-OF-SELECTION.

  SELECT * INTO CORRESPONDING FIELDS OF TABLE GT_ALV2
    FROM TVKO UP TO 100 ROWS
    WHERE BUKRS <> ''
    ORDER BY BUKRS VKORG.


  LOOP AT GT_ALV2 INTO GS_ALV2 WHERE ( SELE = '' ) GROUP BY ( BUKRS = GS_ALV2-BUKRS )
        ASCENDING REFERENCE INTO DATA(LT_GROUP).

    CLEAR: GS_ALV1T.
    CLEAR: GT_ALV1T[].
    CLEAR: GT_ALV2T[].

    LOOP AT GROUP LT_GROUP ASSIGNING FIELD-SYMBOL(<FS_DATA>).
      GS_ALV1T = CORRESPONDING #( <FS_DATA> ).
      GT_ALV1T = VALUE TYT_ALV1( BASE GT_ALV1T ( CORRESPONDING #( <FS_DATA> ) ) ).

      GT_ALV2T = VALUE TYT_ALV2( BASE GT_ALV2T ( CORRESPONDING #( <FS_DATA> ) ) ).
    ENDLOOP.

  ENDLOOP.