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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.<br>
<br>
Matthias<br>
<br>
<div class="moz-cite-prefix">On 05/28/2014 10:54 PM, Bob and Deb
wrote:<br>
</div>
<blockquote
cite="mid:CAHEX0wwH6Qf9RJbEDAfmX0Jkph=GdtBLEzuFDg-X+aZmrNyOhQ@mail.gmail.com"
type="cite">
<p dir="ltr">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?</p>
<p dir="ltr">-Bob (aka cgs_bob on freenode)</p>
<div class="gmail_quote">On May 27, 2014 6:04 AM, "Régis Haubourg"
<<a moz-do-not-send="true"
href="mailto:regis.haubourg@eau-adour-garonne.fr">regis.haubourg@eau-adour-garonne.fr</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
Hugo Mercier wrote<br>
> Or<br>
>> calculated fields in view can't be explicitly cast,
so QGIS should have<br>
>> to<br>
>> guess data type based on a data scan (a major
unadressed issue of sqlite)<br>
><br>
> Hmmm I wasn't aware of this limitation in SQLITE views :(<br>
<br>
Yes, SQLITE does dynamic typing, so user or provider has to
scan values to<br>
guess the right type.<br>
Here is a sqlite topic on that [0]<br>
And here my initial post in qgis list [1]<br>
<br>
[0]<br>
<a moz-do-not-send="true"
href="http://sqlite.1065341.n5.nabble.com/Computed-columns-in-VIEWs-return-NULL-but-should-be-able-to-be-typed-Any-ideas-td56769.html#a56770"
target="_blank">http://sqlite.1065341.n5.nabble.com/Computed-columns-in-VIEWs-return-NULL-but-should-be-able-to-be-typed-Any-ideas-td56769.html#a56770</a><br>
<br>
[1]<br>
<a moz-do-not-send="true"
href="http://osgeo-org.1560.x6.nabble.com/Spatialite-can-t-type-fields-of-a-view-td5058436.html"
target="_blank">http://osgeo-org.1560.x6.nabble.com/Spatialite-can-t-type-fields-of-a-view-td5058436.html</a><br>
<br>
<br>
<br>
<br>
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