Topic: Operation singularity group by at left join in Oracle 12c, a bug or a feature?
Good afternoon, with the following singularity of operation group by at left join in Oracle 12c
I will give an example:
create table temp_22112017_inn as select 1 inn from dual union select 2 from dual union select 3 from dual / create table temp_22112017_inn_sum as select 1 inn, 500 summ from dual union select 2, 600 summ from dual union select 3, 300 summ from dual /--Ïî÷åìó òóò íå âîçíèêëî îøèáêè êàê ýòî áûëî â 11ñ select inn, summ from (select a.inn, summ from (select distinct inn from temp_22112017_inn) a left join (select inn, sum (summ) summ from temp_22112017_inn_sum b group by inn) b on a.inn = b.inn) group by inn / /* drop table temp_22112017_inn; drop table temp_22112017_inn_sum; oracle database 12c enterprise edition release 126.96.36.199.0 - 64bit production */
It is absolutely not clear, why there was no error thus, what the aggregate on summ how it was in 11 is not specified?
Thus deduces similar simply record, or throws off the right part of request.
Who can help that it: the Bug or a feature? If the feature it is not clear as it works?