What spatial functions are available to shapefiles as "virtual layers" in QGIS DB Manager?

Question

Can anyone provide a list of the spatial functions available in the QGIS DB Manager plugin when using shapefiles as Virtual Layers?

I've been trying to use things like ST_DWithin and even ST_Buffer but the queries fail - though ST_Intersects and other functions work just fine.

underdark · Accepted Answer · 2016-12-09T19:05:51.850

2

ST_Buffer works for me.

The virtual layer documentation states:

The underlying engine uses SQLite and Spatialite to operate. It means you can use all of the SQL your local installation of SQLite understands. Functions from SQLite and spatial functions from Spatialite can also be used in a virtual layer query.

The airports layer in this example is as Shapefile from the QGIS sample data.

edited Dec 09 '16 at 19:05

answered Dec 09 '16 at 17:01

underdark

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ST_Buffer doesn't work on shapfiles... if you can verify, that would be great... otherwise, yes... can't find a reference either! Is that all part of the plugin itself? – DPSSpatial_BoycottingGISSE Dec 09 '16 at 18:38
The airports layer in my screenshot example is a Shapefile. DB Manager is a core plugin. You can also create Virtual layers from the menu Layer | Add Layer – underdark Dec 09 '16 at 18:42
I don't understand what's going on then... I can't buffer or transform geometry from a shapefile but I can intersect... – DPSSpatial_BoycottingGISSE Dec 09 '16 at 18:47
Maybe there is an issue on your platform. Which operating system are you using? – underdark Dec 10 '16 at 13:37
Tried at home on Linux Mint to no avail either... tried different data, can't get it to work... – DPSSpatial_BoycottingGISSE Dec 10 '16 at 18:36

What spatial functions are available to shapefiles as "virtual layers" in QGIS DB Manager?

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