SAP/ABAP: Import/Export Memory

FORM u922 USING b_result.

  DATA: itab TYPE TABLE OF bseg,
        jtab TYPE TABLE OF bseg,
        wa   TYPE bseg,
        ls_itab TYPE bseg.

*Varsa memorydeki kayıtları okuyorum...
  IMPORT itab TO jtab FROM MEMORY ID 'MEM_BSEG'.
  MOVE bseg TO wa.

  IF jtab[] IS INITIAL.

    APPEND wa TO itab.
    EXPORT itab TO MEMORY ID 'MEM_BSEG'.

  ELSE.

    FREE MEMORY ID 'MEM_BSEG'.
    itab[] = jtab[].

    CLEAR: ls_itab.

    READ TABLE itab INTO ls_itab
    WITH KEY bukrs = wa-bukrs
             belnr = wa-belnr
             gjahr = wa-gjahr
             buzei = wa-buzei.

    IF sy-subrc NE 0.
      APPEND wa TO itab.
    ELSE.
      MODIFY itab FROM wa.
    ENDIF.

    EXPORT itab TO MEMORY ID 'MEM_BSEG'.

  ENDIF.

  IF sy-ucomm EQ 'BP'.
    READ TABLE itab INTO wa
    WITH KEY koart = 'K'.

    IF sy-subrc NE 0.

      MESSAGE ID 'ZSP_FI'
           TYPE 'E'
         NUMBER '424'
   DISPLAY LIKE 'W'
           WITH bkpf-bukrs.

    ENDIF.
  ENDIF.