TABLE ILLEGAL STATEMENT error with MODIFY command

Question

Hi gurus,
i want you to inform me about table illegal statement error. The error occurs when i use modify as below.
loop at itab.
   select .......
         where xxx eq itab-xxxx.
       MODIFY itab.
  endselect.
endloop.
i know that i have to give the sy-tabix as INDEX parameter to the modify command. but i want to know why i have to do this?
cause when i debug, i follow the sy-tabix field and it have not a change in select endselect.
may the reason of the error about cursor in select and cursor effects modify command?
or why?
Thx,

Answer 1

Hello,
I guess this is because your MODIFY statement is inside the SELECT ... ENDSELECT & not inside the LOOP ... ENDLOOP.
SAP documentation says:
Within a LOOP loop, the INDEX addition can be ommitted. In this case the current table line of the LOOP loop is changed.
You have to change the coding:
DATA: v_index TYPE i.
loop at itab.
v_index = sy-index.
select .......
where xxx eq itab-xxxx.
MODIFY itab INDEX v_index.
endselect.
endloop.
BR,
Suhas
PS: The coding practice followed is not very performance oriented as well. May be you should have a look around in some blogs, wikis in SCN & change the code accordingly.
Edited by: Suhas Saha on Nov 19, 2009 9:41 AM