SELECT statement INTO TABLE - what determines order of entries in in.table?

Question

Hello everyone.
I habe a question: A select statement selects multiple entries from a data base table that are put into an internal table.
The question : What determines the order of the entries in the internal table? 
And what might change the order all of a suddden in that internal table?
Could reorg. activities/archiving (even ongoing) cause any different result in the order as before ?
I do not mean different entries but I rather refer to the sorting of the internal table, if it is not explicitly stated in the select or in parts of the coding.
Any explaination is appreciated!
Thanks!
CN.

Answer 1

Hi,
Its not the order in which you specify the fields in the where clause that affects the sequence of the selection.
What I said is that by default the entries are sorted by the primary key of the table.
I did a bit of a test out of curiosity and after seeing so many different replies on the thread. I was surprised to see the results of the different scenarios.
REPORT  Z_TEST_SELECTION                        .
tables vbap.
data it_vbap type table of vbap.
data it_vbak type table of vbak.
select-options s_vbeln for vbap-vbeln.
select-options s_posnr for vbap-posnr.
"======================================================================
"s_vbeln has following entries
" 5
" 6
" 1
" 2
"s_posnr has following entries.
" 10
" Sorts in ascending order by VBELN and POSNR by default
select * up to 20 rows from vbap into table it_vbap.
refresh it_vbap.
"Below two cases are absolutely unreliable and I would suggest that a
"sort should be mentioned after these statements. So when we use select
"options specify values with the in clause, the sort is not reliable.
"Strangely , neither the sequence is not determined by the order in
"which the data was entered in the select option nor in the sequence of
"the primary key. And this is still a mystery to me about the order in which
"the entries are selected.
" Any answeres anyone ?
"1.
select * from vbap into table it_vbap
where  vbeln in ('0000000002','0000000006','0000000005','0000000001')
and posnr in s_posnr.
* Resulted in
*900  |0000000001|000010|
*900  |0000000005|000010|
*900  |0000000006|000010|
*900  |0000000002|000010|
"=========================================================
"2.
select * from vbap into table it_vbap
where  posnr in s_posnr
and    vbeln in s_vbeln.
* Resulted in
*900  |0000000002|000010|
*900  |0000000001|000010|
*900  |0000000005|000010|
*900  |0000000006|000010|
refresh it_vbap.
"Here the orders were selected in Decending order of Sales order, however
"the posnr is not mentioned in the order by clause, hence posnr was
"still in ascending order.
select * from vbap into table it_vbap
where posnr in s_posnr and vbeln in s_vbeln
order by vbeln descending.
write : 'done!'.
refresh it_vbap.
"Here the orders were selected in Descending order of Sales order.
select * from vbak into table it_vbak where vbeln in s_vbeln
order by vbeln descending.
" The entries were selected in the ascending order of the key VBELN and
" POSNR, so it seems that for all entries does not affect the selection of records.
select * from vbap into table it_vbap
for all entries in it_vbak
where vbeln = it_vbak-vbeln
and   posnr in s_posnr.
Of course if you change the order of the primary key (in the transparent table, not in the where clause), the entries will be sorted as per the changed key.
But we seldom change the the sequence of the primary key. In most cases we normally add a new field and make it a key field in addition to the existing key fields.
I hope this helps you.
There might be many more cases and examples than given above, which you can try and reply on this post. Lets see what we come up with.
regards,
Advait