2

I have:

  • a non-spatial table of multiple test results with reference to non-unique locations, and

  • a spatial layer that has all the locations (multiple results per location)

I can do table joins between the locations layer to the results, but I get stuck because each location has multiple results...

I suspect I need to make a virtual layer assigning the geometry to each result, but I get lost at the "query" stage. The QGIS manual goes deep into database SQL queries but I am hoping there is a simpler solution for the non-initiated?

Note: I can create virtual "x" and "y" attribute columns and join them to my table, but still missing a step to use the coordinates in creating the virtual layer

  • Please add a sample of your tests / locations and the desired output. – JGH Oct 16 at 11:44
  • Sorry @JGH - I should have. I am still struggling a bit with the formatting of questions, inserting tables and images, etc. The example Luis provided below is perfect thought, and his answer is spot on. – Benoit_W Oct 16 at 22:41
2

Virtual layer is your answer :

for example two tables,

nonspatial table:
id|Restaurant|costumer
1 | Rest1    | george
2 | Rest1    | Peter
3 | Rest2    | grace
4 | Rest2    | Peter


spatial table:
id | Restaurant | geometry
1  | Rest1      | Point(1,0)
2  | Rest2      | Point(1,2)
3  | Rest3      | Point(2,0)

your query

select "nonspatial".*, "spatial"."geometry" 
from "nonspatial", "spatial"
where "nonspatial"."Restaurant"="spatial"."Restaurant"

Result

id|Restaurant|costumer|geometry
1 | Rest1    | george |Point(1,0)
2 | Rest1    | Peter  |Point(1,0)
3 | Rest2    | grace  |Point(1,2)
4 | Rest2    | Peter  |Point(1,2)

tip - if your tables and columns are in lowercase, quotes are not necessary

  • This is awesome Luis, thank you so much. The query is extremely easy to read and I replicated with the actual data on first try. I did not realise accessing the geometry of the spatial table was that easy! I really need to learn more about spatial query - is there a gentle introduction / manual that I could start with? – Benoit_W Oct 16 at 22:37
  • 1
    you are welcome.. my sql knowledge came from postgis and postgres but for start i think spatialite is very powerful. [gaia-gis link]( gaia-gis.it/gaia-sins/spatialite-tutorial-2.3.1.html) – luis Rafael Oct 17 at 12:24

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