CALL BDC 时各参数

以前作过这样的程序,记录一笔. 

DATA: MESSTAB LIKE BDCMSGCOLL OCCURS 0 WITH HEADER LINE.

 CALL TRANSACTION 'VA21'
       USING BDCDATA
      mode  mode "'A'                    " display screen
*      mode   'E'            " Display screen only if an error occurs
**       MODE   'N'                      " No display
       UPDATE 'S'                      " Synchronous update
       MESSAGES INTO MESSTAB. 

* process error
  IF SY-SUBRC NE 0.

    LOOP AT MESSTAB.
      WRITE: / MESSTAB.
    ENDLOOP.
  else.

    write: / sy-msgv1,  sy-msgv2.
  ENDIF.