Idea for this code pls

Question

Hi,
In the below code, I have certain doubts.
1.Do I need to go for inner join statements in fetching data for parameters?..
2. How can I group by document type and print the total of net value...for this do i need to move the datas to another internal table ?..How to ?
tables : vbak,vbap.
data : begin of itab occurs 0,
        vbeln like vbak-vbeln,
        auart like vbak-auart,
        netwr like vbak-netwr,
        waerk like vbak-waerk,
        zmeng like vbap-zmeng,
        zieme like vbap-zieme,
        posnr like vbap-posnr,
        matnr like vbap-matnr,
        end of itab.
select-options : s_vbeln for vbak-vbeln.
Parameters     : s_vkorg(10) type c,
                 s_vtweg(10) type c,
                 s_spart(10) type c.
start-of-selection.
select avbeln aauart anetwr awaerk bzmeng bzieme bposnr bmatnr
into table itab from vbak as a inner join vbap as b on b~vbeln =
avbeln where avbeln in s_vbeln .
loop at itab.
write : /5 itab-vbeln,15 itab-posnr,25 itab-auart,
30 itab-matnr,35 itab-zmeng,40 itab-zieme,45 itab-netwr,50 itab-waerk..
endloop.
Initialization.
at selection-screen.
IF   s_vbeln is initial and
     s_vkorg is initial and
     s_vtweg is initial and
     s_spart is initial.
    MESSAGE e000(zam).
  ENDIF.
  IF not s_vbeln is initial.
   select vbeln  auart netwr waerk from vbak into table itab where vbeln
                                                             in s_vbeln.
    IF sy-subrc NE 0.
         MESSAGE e001(zam).
             ENDIF.
    else.
    if not  s_vkorg is initial.
     select vbeln auart netwr waerk from vbak into table itab
                                     where vkorg = s_vkorg.
         if sy-subrc NE 0.
             message e002(zam).
                     endif.
                      endif.
    If not s_vtweg is initial.
     select vbeln auart netwr waerk from vbak into table itab
                                      where vtweg = s_vtweg.
       If sy-subrc NE 0.
            message e003(zam).
                  endif.
                   endif.
     if not s_spart is initial.
        select posnr matnr zmeng zieme from vbap into table itab
                                           where spart = s_spart.
        if sy-subrc NE 0.
             message e004(zam).
                 endif.
                   endif.
   ENDIF.

Answer 1

The JOIN looks OK.
You can move the document type to the beginning of the internal table and sort on it when the data is collected.Then:
  LOOP AT itab.
    AT NEW auart.
* Totals
    ENDAT.
    WRITE :  /5 itab-vbeln,15 itab-posnr,25 itab-auart,
             30 itab-matnr,35 itab-zmeng,40 itab-zieme,
             45 itab-netwr,50 itab-waerk..
  ENDLOOP.
Rob