Re: problem with query and group by error

Susan Cassidy-3 wrote
> I have a large query:
>    SELECT distinct on (srs.scan_run_id) srs.scan_run_id,
> srs.run_request_number, srs.container_id, srs.manifest_id,
> srs.scan_system_name_id,
>        srs.scan_site_name_id, srs.scan_site_nickname_id,
> to_char(srs.start_time, 'MM/DD/YY HH24:MI:SS'),
>        to_char(srs.stop_time, 'MM/DD/YY HH24:MI:SS'), srs.system_operator,
>        srs.system_baseline_configuration_file_version_id,
> srs.container_contents, srs.container_run_truth_data,
>        srs.scan_type_id, sty.scan_type,
> srs.hardware_version_or_hardware_identifier_id,
>        srs.software_version_id, srs.operator_notes,
>        to_char(srs.expiration_date, 'MM/DD/YY HH24:MI:SS'),
> srs.scan_outcome_id,
>         to_char(srs.alarm_time, 'MM/DD/YY HH24:MI:SS'),
> srs.alarm_decision_id, srs.material_detected_id, srs.data_access,
>           ssn.scan_system_name, ssn.simulation, ssitenames.scan_site_name,
> ssitenicknames.scan_site_nickname,
>           hvhi.hardware_version_or_hardware_identifier_name,
> sv.software_version, sc.description
>       from scan_run_summary srs left outer join scan_system_names ssn on
>              srs.scan_system_name_id = ssn.scan_system_name_id
>          left outer join scan_site_names ssitenames on
> srs.scan_site_name_id = ssitenames.scan_site_name_id
>          left outer join scan_site_nicknames ssitenicknames on
>            srs.scan_site_nickname_id =
> ssitenicknames.scan_site_nickname_id
>          left outer join hardware_version_or_hardware_identifiers hvhi on
> srs.hardware_version_or_hardware_identifier_id =
>           hvhi.hardware_version_or_hardware_identifier_id
>          left outer join software_versions sv on srs.software_version_id =
> sv.software_version_id
>          left outer join scenes sc on srs.container_run_truth_data =
> sc.scene_id
>          left outer join scan_types sty on srs.scan_type_id =
> sty.scan_type_id
>           join scene_thing_instances sti on srs.container_run_truth_data =
> sti.scene_id
>  join scene_things stg on sti.scene_thing_id = stg.scene_thing_id
>   group by srs.scan_run_id
> ;
>
>
> That gives this error:
>
> ERROR:  column "sty.scan_type" must appear in the GROUP BY clause or be
> used in an aggregate function
> LINE 5:        srs.scan_type_id, sty.scan_type, srs.hardware_version...
>
> I don't see why sty.scan_type should be singled out as requiring a group
> by
> clause, when there are many other columns specified.
>
> If I add scan_type to the group by, then it gives the same error, but with
> ssn.scan_system_name.
>
> Am I going to have to specify all the columns in the group by clause?
>
> I originally had the query without the group by, but I had duplicate rows,
> so I added a group by to eliminate them.
>
> Thanks,
> Susan

Newer releases (not sure which) are capable of identifying a primary key in
a group by and allow you to omit all dependent columns of said primary key.

However, as a general rule, every non-aggregated column must appear in the
GROUP BY.  There is not "default behavior" for columns not appearing in
group by nor that have been aggregated.

David J.





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