I have a layer (my_layer) containing a virtual field (virtual_1). Next step I want to create a virtual layer, which list only unique values (as an bonus also dissolves the geometries by unique values).

The following query for the virtual layer does not work with virtual fields:

SELECT DISTINCT virtual_1 from my_layer 

How could the desired outcome be achieved?

Some notes/ideas:

• I need an dynamic solution, as the data in "my_layer" gets updated reguarly. So unfortunately the Vector>Analysis>Unique Values is not an option. Also Dissolving by virtual field is therefore not an option.
• Would it work to generate the virtual field inside the Query itself? How could an expression of the field editor evaluated in the virtual-field-query?

I have a layer my_layer containing a virtual field virtual_1. Next step I want to create a virtual layer, which list only unique values (as a bonus also dissolves the geometries by unique values).

The following query for the virtual layer doesn't work with virtual fields:

SELECT DISTINCT virtual_1 from my_layer 

How could the desired outcome be achieved?

Some notes/ideas:

• I need an dynamic solution, as the data in my_layer gets updated reguarly. So unfortunately the Vector>Analysis>Unique Values isn't an option. Also Dissolving by virtual field is therefore not an option.
• Would it work to generate the virtual field inside the query itself? How could an expression of the field editor evaluated in the virtual-field-query?