Nested LOOPs - Do you recommend?

[Former Member]

Hi,

I am using a nested LOOP in my print program that uses a form in SAPScript. Please see the code fragment:

LOOP AT it_final INTO wa_final.

LOOP AT it_mseg INTO wa_mseg.

CALL FUNCTION 'WRITE_FORM'

EXPORTING

element = 'HEAD'

type = 'TOP'

window = 'MAIN'.

CALL FUNCTION 'WRITE_FORM'

EXPORTING

element = 'INFO'

type = 'BODY'

window = 'MAIN'.

ENDLOOP.

ENDLOOP.

The internal table IT_MSEG usually contains only minimal number of lines, say less than 10. I can't find an alternative in this particular scenario. Is it gonna make the system considerably slower?

[Former Member]

Hi,

try to use where condition for your second loop base on the values from 1st internal table, may be you have 10 rec in development when coming to production system there may be a chance of getting more records.

Reward if useful.

Thanks,

Sreeram.

[Former Member]

Dear Sreeram,

Data in IT_MSEG is already filtered based on input in select-options. The problem with your suggestion is, there is no direct link between IT_FINAL and IT_MSEG.

Arun.

[Former Member]

Instead of using nested Select loops it is often better to use subqueries

Check the following link:

how to avoid nested loops in this program to improve the performence

Reward points if useful.

[Former Member]

Sravan,

I'm not talking about nested selects. I'm using nested "LOOP AT". In the loop, I'm not touching the database at all.

[Former Member]

Hi Arun,

IF it_final is your header level and it_mseg is your item level then I dont think you can avoid this nested loop.

But if you have to select a single entry from it_mseg, then you can do like this,

LOOP AT it_final INTO wa_final.

READ TABLE it_mseg INTO wa_mseg.

CALL FUNCTION 'WRITE_FORM'

EXPORTING

element = 'HEAD'

type = 'TOP'

window = 'MAIN'.

CALL FUNCTION 'WRITE_FORM'

EXPORTING

element = 'INFO'

type = 'BODY'

window = 'MAIN'.

ENDLOOP.

Regards

Sourabh Verma

[Former Member]

Thats the problem Sourabh, It is not a single entry that i take from IT_MSEG. IT_FINAL is at header level. IT_MSEG has line items.

[rodrigo_paisante3]

Hi, see this link:

/people/rob.burbank/blog/2006/02/07/performance-of-nested-loops

Rob recomends the indexed or parallel loop...

Regards

[Former Member]

Dear Rodrigo,

That blog by Rob was really worth. Thanks. Thanks to all.

Regards

Arun.

[Former Member]

For nested loops problem, go for parellel cursor technique , an eg. simmilar to ur req. header and line item can be printed/processed in the manner as given below.

SORT : it_mara BY matnr ,

it_makt BY matnr .

i = 1.

LOOP AT it_mara INTO wa_mara.

LOOP AT it_makt INTO wa_makt FROM i.

IF wa_makt-matnr <> wa_mara-matnr.

i = sy-tabix.

EXIT.

ENDIF.

write 😕 wa_mara-matnr , wa_makt-MAKTX .

ENDLOOP.

ENDLOOP.

PS: Reward Poins if Helpfull.

Regards

Naveen Gupta

[Former Member]

Thanks for that Naveen. It helped.