Nehtdx

I have a memory layer loaded in the QGIS virtual layer in the data source manager. I am trying to run a very simple query:

select * from layer

Here is a snapshot:

While this works for the physical layer, it does not work for the memory layer. They output virtual layer is blank, and I know that my memory layer has attribute data.

Is this simply a bug? I want to keep this a memory layer to reduce the number of steps I need to do to arrive at my final result. Should I resort to another tool or is there a workaround?

EDIT

Also found this quote in this link:

Creating a virtual layer with the layer_ref key allows to directly access already loaded QGIS layers (including memory layers).

The upper section, embeded layers, allows listing (and using) layers that are not loaded in QGIS table of content.

Using an in-memory layer that is not loaded in QGIS is to be tested. I believe the layer is cleared from memory as soon as it is removed from the table of content.

If you do have the in-memory layer loaded in the table of content, you can simply remove it from the embeded layers section, and the query will work. I just reproduced your use case and workaround in 3.4.5

You can find all your layers in the DB-manager. There (in my opinion) it is easier to access and query them. And you can load results as a new layer.

• Go to DB-manager > Virtual Layers > QGIS layers




• Select one of the layers and make your query. Note that the geometry is written as geometry and not geom.