Virtual Layer query connection failed at reload project

Question

I have a QGIS project that generates a layer with point geometry from a database (Excel sheet) that I load directly into QGIS. To this table a join is established with a common field of a GPKG point geometry layer.

The virtual layer is created with the option Layer / Add layer / Add-Edit virtual layer and use MakePoint(longitude, latitude, CRS) to create the geometry:

SELECT myID, 
       myField, 
       MakePoint(myLong,myLat,3857) as geometry
FROM   myTable

The point geometry layer is created as expected. The problem appears when I want to recover (open) the project after having closed it. There seems to be some problem retrieving the query.

I have added an animated screenshot that tries to show the workflow:

Answer 1

I don't know why the virtual layer is failing at reload. But as a work around I think you could include the join logic directly in the virtual layer. Try this for the virtual layer definition:

SELECT DOMCOD, GEOX_CARTO.GEOMETRY as Geometry FROM POSTALCODE1 
JOIN GEOX_CARTO ON POSTALCODE1.REF14 = GEOX_CARTO.Campo2

With this query the virtual layer joins the POSTALCODE1 table to the GEOX_CARTO table and retrieves the point geometry directly. No need to create the join in the the Layer Properties to get the lat and long and then create a point from the coordinates.