[Qgis-developer] have aggregate/window expressions ever been discussed?

[Matthias Kuhn]

Using the foreign key constraints to propose automatically created 
relations to the user would be a nice feature for any database. One 
problem here is, that the providers handle the database management 
themselves and only provide QGIS the information that there is a layer, 
but not from what database it comes. Maybe it would be possible to 
extract this information with the current architecture but for an 
optimal handling the provider architecture should be adapted to provide 
such information in a standard way.

Matthias

On 05/28/2014 10:54 PM, Bob and Deb wrote:
>
> How about querying the sqlite_master table to find the data type?  And 
> why not use the constraints found in this query to set up the qgis 
> relations?
>
> -Bob (aka cgs_bob on freenode)
>
> On May 27, 2014 6:04 AM, "Régis Haubourg" 
> <regis.haubourg at eau-adour-garonne.fr 
> <mailto:regis.haubourg at eau-adour-garonne.fr>> wrote:
>
>     Hugo Mercier wrote
>     > Or
>     >> calculated fields in view can't be explicitly cast, so QGIS
>     should have
>     >> to
>     >> guess data type based on a data scan (a major unadressed issue
>     of sqlite)
>     >
>     > Hmmm I wasn't aware of this limitation in SQLITE views :(
>
>     Yes, SQLITE does dynamic typing, so user or provider has to scan
>     values to
>     guess the right type.
>     Here is a sqlite topic on that [0]
>     And here my initial post in qgis list [1]
>
>     [0]
>     http://sqlite.1065341.n5.nabble.com/Computed-columns-in-VIEWs-return-NULL-but-should-be-able-to-be-typed-Any-ideas-td56769.html#a56770
>
>     [1]
>     http://osgeo-org.1560.x6.nabble.com/Spatialite-can-t-type-fields-of-a-view-td5058436.html
>
>
>
>
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