ABAP FIELD SYMBOL's - Techniques for manupulating data using the FIELD-SYMBOL's

*Code to demonstrate field-symbols

REPORT  zfield_symbols                                                 .

TYPES: BEGIN OF t_p0121,
 pernr TYPE pa0121-pernr,
 rfp01 TYPE pa0121-rfp01,
 rfp02 TYPE pa0121-rfp02,
 rfp03 TYPE pa0121-rfp03,
 rfp04 TYPE pa0121-rfp04,

 END OF t_p0121.

DATA: it_p0121 TYPE STANDARD TABLE OF t_p0121 INITIAL SIZE 0,
      wa_p0121 TYPE t_p0121.

DATA: gd_index TYPE string,
      gd_rfp0 TYPE string.

FIELD-SYMBOLS: <fs1>, <fs2>.

************************************************************************
*Start-of-selection.
START-OF-SELECTION.

  SELECT pernr
         rfp01
         rfp02
         rfp03
         rfp04
   UP TO 10 ROWS
    FROM pa0121
    INTO TABLE it_p0121.

************************************************************************
*End-of-selection.
END-OF-SELECTION.

WA_P0121-RFP01 = '1234'.
CONCATENATE 'WA_P0121-RFP01'  gd_index INTO gd_rfp0.

* Now watch how the values change as you loop around the table fields
  LOOP AT it_p0121 INTO wa_p0121.
    write:/.
    write:/ wa_p0121-pernr.
    CLEAR: gd_index.
    DO.
      gd_index = gd_index + 1.
      CONCATENATE 'WA_P0121-RFP0'  gd_index INTO gd_rfp0.

* assign with brackets
      ASSIGN (gd_rfp0) TO <fs1>.  "assigns the value of field name contained in variable
* fs1 value would be the value of the field WA_P0121-RFP01..21
* i.e. if index 1 and WA_P0121-RFP01 = 1234 then fs1 would = 1234

* assign without brackets
      ASSIGN gd_rfp0 TO <fs2>. " assigns the exact value contained in the field
* fs1 value would literally be the same as the field WA_P0121-RFP01..21
* i.e. if index 1 then fs2 would = 'WA_P0121-RFP01'
*         index 2 then fs2 would = 'WA_P0121-RFP02' etc...

* you may also notice that once assigned any change made to the field gd_rfp0
* is instantly reflected in the field symbol (fs2) so technically you could perform
* the assign command once outside of the loop, but i have left it here to aid
* readability.
      write:/ <fs2>, <fs1>.
      IF gd_index GE 21. "exit once last field has been read
        EXIT.
      ENDIF.
    ENDDO.
  ENDLOOP.

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