Va02 screen input first save it has to update the data base table

Question

I am working on VA02.
For only one user(delivery block)should be block and when we are changing in sales order document for that user it has to update the VBAK table.
for second save i'm able to updating but i want to update at first save only.
thanks,
sree.

Answer 1

I want to update the DB table VBAK. and the user exit is:
here is my coding: my requirement is to block a field i.e LIFSK in va02 and after saving that and i have checked vbak table then in lifsk the blocked db is updated IN TABLE CONTENTS.LATER IF I SAVE IT ANOTHER TIME WITHOUT ANY MODIFICATIONS THE FIELD IS NOT UPDATED.
now the problem is with updation .i have blocked the field.
Please help me  its urgent
FORM USEREXIT_MOVE_FIELD_TO_VBAK.
tables: knkk.
if not vbak-kunnr is initial.
  if vbak-auart NE 'ZFD' and
     vbak-auart NE 'ZCR2' and
     vbak-auart NE 'ZRE' and
     vbak-auart NE 'ZSD'.
    select single * from KNKK
      where  KUNNR = vbak-kunnr
      and    KKBER = '8000'.
      if sy-subrc = 0.
        clear vbak-LIFSK.
      ENDIF.
      IF NOT SY-UNAME = 'FINCOMM1' AND SY-TCODE = 'VA02'.
          SELECT SINGLE LIFSK FROM VBAK INTO LIFSK1 WHERE VBELN = VBAK-VBELN.
           IF LIFSK1 NE ' '.
              vbak-LIFSK = ' '.
           ELSEif vbak-auart eq 'ZCR2'.
                  vbak-LIFSK = 'Z1'.
              ELSE.
                  vbak-LIFSK = 'Z6'.
           endif.
         if sy-tcode eq 'VA02' . "added on 22/05/2008
        if screen-name = 'VBAK-LIFSK'.
              screen-input = 1.
              modify screen.
              update vbak.
        endif.
  ENDIF.
      ENDIF.
  endif.
endif.
  if sy-tcode eq 'VA02' AND sy-uname NE 'FINCOMM1'. "added on 22/05/2008
        if screen-name = 'VBAK-LIFSK'.
          screen-input = 1.
              modify screen.
              update vbak.
        endif.
endif.
endform.
Thanks,
sri.