Topic: QGIS update table column with join to another table


I thought I had figured out how to do this, but if I have, I've forgotten.

This is what I would call a classic operation for LERC GIS people.  I have a set of point records and a set of polygon records.  I want to update a field in the point records with information from the polygon records, depending on which polygon each point record falls in geographically.  Put another way, I want to label each point record with the name of the polygon that contains it.

I think typically LERC people might do this kind of thing to label a set of species records with the name of local wildlife sites they were recorded in, or something like that.

In MapInfo, you would use "update column" where you would be able to choose other tables that you currently have open.  You would then define the join between the two tables.  In this example, by saying "where object from table one is within object from table two".  It's very straight forward.

It might be straight forward in QGIS, but I can't work it out.  I can't seem to Google the correct question to find relevant help either.  There is an expression builder in order to update columns, but I can't see how to include fields from other tables.

Any help would be greatly appreciated.


Tom Hunt - ALERC National Coordinator

Re: QGIS update table column with join to another table

You can go to vector > data management tools > join attributes by location.

You can then pick to the two tables in question and create a new layer which contains all the attributes from both tables.  This is not exactly what I hopped for, because I will now have to delete all the columns from the second tables that I don't need.  However, the final result will be what I was after.

This means I can share some RSPB swift records soon.  They were originally shared via the Gateway, but as the Gateway can't currently share them at full resolution, I have been asked to share them in GIS format.


Tom Hunt - ALERC National Coordinator