topic Re: DELETE records within the loop in Application Development and Automation Discussions

DELETE records within the loop

former_member197475 — Fri, 18 Apr 2014 05:41:52 GMT

Hi Experts,

I just read some of the threads in SCN and all have prescribed to avoid DELETE statement inside the loop.

See me case below. I have two local tables lt_beleg and lt_rot.

LOOP AT lt_beleg into lw_beleg.

DELETE lt_rot where BELNR = lw_beleg-BELNR.

END LOOP.

Am deleting records from lt_rot based on the BELNR from lt_beleg. But my lt_rot contains possible records where BELNR = ' '. So I dont have any other option to delete the records within loop, such that i'll will have records with other than BELEG as well as empty BELNR in my lt_rot.

I don't understand how it will affect the performance, as am deleting the records with exact condition within the loop.

Please help me to clear it, else is there any other way to handle the code.

Waiting for your valuable ideas

BR,

RAM.

Re: DELETE records within the loop

Arun_Prabhu_K — Fri, 18 Apr 2014 06:11:55 GMT

Hello Ramakrishnan.

I don't where you read about it, but using DELETE itab looping the same itab is only not advisable.

For instance,

loop at itab where field = value.

delete itab.

endloop.

Instead delete itab where field = value is the best way.

Regards.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 06:28:17 GMT


K.Arun Prabhu wrote:

.., but using DELETE itab looping the same itab is only not advisable.

Not correct. While DELETE ... WHERE is preferred, there is absolutely nothing wrong with

LOOP AT itab INTO wa.

IF some complicated condition is met.

DELETE itab.

ENDIF.

ENDLOOP.

You might find

LOOP AT itab ASSIGNING <record>.

IF some complicated condition is met.

DELETE <record>.

ENDIF.

ENDLOOP.

more problematic, as <record> becomes unassigned. HASHED tables need more care with the delete, but the principle holds: generally there is no issue.

Re: DELETE records within the loop

former_member193512 — Fri, 18 Apr 2014 06:31:57 GMT

Dear RamaKrishnan

you can try this way ...

with in the loop , if the condition satisfies set the flag variable and then delete the records after the loop if the flag is set.

LOOP AT lt_beleg into lw_beleg.

IF <CONDITION>.

move 'x' to flag.

ENDIF.

END LOOP.

DELETE lt_rot where flag eq 'x'.

hope it helps.

Re: DELETE records within the loop

Arun_Prabhu_K — Fri, 18 Apr 2014 06:33:53 GMT

Matthew,

You are right. I should have phrased it better.

I meant for the case wherein there is no check involved inside loop but only just plain DELETE statement.

Regards.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 06:36:16 GMT

That's nonsense. This program simply will not work.

If you wanted to do something similar, you'd have to update a delete flag field in each record of the table, But what would be the point? You might as well put the delete in the loop. You're just making the program more inefficient.

Re: DELETE records within the loop

srikanthv2 — Fri, 18 Apr 2014 06:42:22 GMT

Hello Ramakrishnan,

Please filter BELNR records while fetching in select query using 'for all entries' without deleting in loop.

For Ex:

if the BELEG and ROT are database tables.

select * from BELEG into table lt_beleg where condition.

if lt_beleg is not initial.

select * from ROT into table lt_rot for all entries in lt_beleg where ( belnr = lt_beleg-belnr and belnr <> space ).

endif.

Regards

Srikanth

Re: DELETE records within the loop

former_member193512 — Fri, 18 Apr 2014 06:49:20 GMT

Dear Matthew Billingham

As Ramakrishnan wrote

" is there any other way to handle the code"

i am trying to answer that , as you told in case of field symbols we cannot delete the record

with in the loop as it unassigns the workarea, i think in that case we can use it ...

if any thing is wrong or if i understood wrongly, could you please correct me ,thankyou.

Thanks

Shravan

Re: DELETE records within the loop

former_member197475 — Fri, 18 Apr 2014 06:53:33 GMT

Dear all,

Thanks for your response.

So I can understand that, I can go ahead with the same coding as am not deleting the it_table with the same looped it_table.

If not, please correct me.

BR,

RAM.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 07:01:09 GMT

You can delete records within the loop with ASSIGNING: You just need to be aware that you can't address the record afterwards.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 07:01:37 GMT

Oh come on. Don't use FOR ALL ENTRIES. Use a JOIN.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 07:04:06 GMT


K.Arun Prabhu wrote:

Matthew,
     You are right. I should have phrased it better.
     I meant for the case wherein there is no check involved inside loop but only just plain DELETE statement.
Regards.

Still doesn't make sense to me. What do you mean "no check involved"? If there's no check, you can't use WHERE in the first place? Anyway I've done things like this quite happily.

LOOP AT itab INTO wa.

<logic>.

DELETE itab.

<more logic>.

ENDLOOP.

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 07:05:47 GMT

If you are solely deleting records that meet a condition, use DELETE...WHERE...

Looping through a table and deleting from that table is not a problem. Depending what you are doing, it might be good programming.

Re: DELETE records within the loop

former_member197475 — Fri, 18 Apr 2014 07:15:29 GMT

Hi Matthew,

Thanks a lot for your well explanation.

Closing this thread.

BR,

RAM.

Re: DELETE records within the loop

former_member197475 — Fri, 18 Apr 2014 07:16:04 GMT

Thanks for your idea Shraven.

BR,

RAM.

Re: DELETE records within the loop

Arun_Prabhu_K — Fri, 18 Apr 2014 07:28:40 GMT

Matthew,

You again got me wrong.

I meant a case exactly like

loop at itab where field = value.

delete itab.

endloop.

Naive programmers usually code as above.
Comparatively, delete itab where field = value is better in terms of performance.

Re: DELETE records within the loop

Former Member — Fri, 18 Apr 2014 07:39:13 GMT

hi,

another way is , create a range for type BELNR.

loop.

fill range r_belnr.

endloop.
after looping , write delete statement.

DELETE lt_rot where BELNR in r_belnr.

regards,

Satyen T.

Re: DELETE records within the loop

Former Member — Fri, 18 Apr 2014 07:39:31 GMT

Hi,

You can aslo try in this way,

Yes, generally it is not advisable to use Delete Statements under the Loop.

But when you want to compare records of another internal table then there is no other go we have to use delete statement under the loop.

I have slightly modified the code, try this off.

SORT lt_beleg by BELNR.

SORT lt_rot by BELNR.

LOOP AT lt_beleg into lw_beleg.

Read table lt_rot into LS_ROT with key BELNR = lw_beleg-BELNR

BINARY SEARCH.

if sy-subrc eq 0.

DELETE lt_rot where BELNR = LS_ROT-BELNR.

endif.

clear: LS_ROT, LW_BELEG.

END LOOP.

Regards,

Saravanan Sambandam

Re: DELETE records within the loop

matt — Fri, 18 Apr 2014 07:58:19 GMT

This is what I disagree with. There is no general principle of not using DELETE in a loop. In many cases it is exactly the thing to do.

Oh, and don't use SORT and BINARY SEARCH. Use SORTED tables - or even better, HASHED tables from the start! They've only been part of the ABAP language for over fifteen years!

Re: DELETE records within the loop

Former Member — Fri, 18 Apr 2014 08:02:30 GMT

bt we can delete the record outside the loop.

DELETE lt_rot where BELNR in r_belnr.

No need to write delete statement within the loop.