[Qgis-developer] Aggregates within expression engine
Bernhard Ströbl
bernhard.stroebl at jena.de
Wed Mar 16 00:56:20 PDT 2016
Hi,
just my 2 ct:
I agree with Paolo that normal users do not know SQL, on the other hand
there might be users that do not know spreadsheet syntax either (e.g. me
:) which spreadsheet BTW: Excel? LO? or do they use the same syntax? SQL
would be a standardized approach (and is the syntax already used in QGIS
expressions). On the other hand if it is possible to "click together"
the expression it doesn't matter which syntax is used, good
documentation and direct help is a must here. If you e.g. choose a SUM
function a GROUP BY woould be added automatically at the end (if not
already there)
SQL is used at so many places in QGIS: layer filters, labelling,
rule-based renderer... I would not mix this with different syntax.
Bernhard
Am 16.03.2016 um 08:36 schrieb Paolo Cavallini:
> Il 16/03/2016 08:30, Neumann, Andreas ha scritto:
>
>> Why do you think SQL aggregate syntax (e.g. as outlined
>> at http://www.postgresql.org/docs/9.5/interactive/functions-aggregate.html)
>> is a no-go? Can you explain this in detail? QGIS is much closer to a
>> database then it is to a spreadsheet - in fact for most serious QGIS
>> work you store your data in a SQL database.
>>
>> It was my impression that QGIS tries to maintain expression syntax
>> compatible with SQL wherever possible. I think it would be a good thing.
>
> Hi Andreas,
> based on my lengthy experience with courses, I'm pretty sure SQL
> commands are out of reach for most "normal" GIS users.
> It is fine to have access to SQL for power users, but aggregate
> functions should IMHO be available to anyone.
> All the best.
>
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