Feature request #11505

One to many / many to one joins

Added by Ed Hudspeth almost 5 years ago. Updated about 2 years ago.

Status:Feedback
Priority:Normal
Assignee:-
Category:Relations
Pull Request or Patch supplied:No Resolution:
Easy fix?:No Copied to github as #:19775

Description

Currently, any join performed on a table is a one to one join - it would be great to perform one to many joins.

Example:
Table A = Towns
Table B = Customers (aspatial)

Join on Town name - currently only returns the first customer name it gets to, it would be good to list all.

History

#1 Updated by Matthias Kuhn almost 5 years ago

  • Status changed from Open to Closed

QGIS relations offer the possibility to define a 1:N relation and integrate with the feature form.

http://fulcrumapp.com/blog/using-relations-in-qgis/
http://blog.vitu.ch/10112013-1201/qgis-relations

#2 Updated by Ed Hudspeth almost 5 years ago

But this doesn't allow you to update a table - you have to click on each object. What about tables with 1000s of records - really need to see the join functionality extended at least to allow you to concatenate all results rather than just take the first.

#3 Updated by Mathieu Pellerin - nIRV over 4 years ago

I don't think this should be closed.

What is needed here is for the join functionality to allow for a 1-to-many join (like an SQL operation would do). It's useful and at times needed to do time series animation through TimeManager, etc.

#4 Updated by Miroslav Umlauf about 4 years ago

I also disagree with closing this. Integration with feature form doesn't really cut it in the case that somebody needs to create new dataset/table which includes all 1:N variations.

#5 Updated by infobleep - about 2 years ago

  • Description updated (diff)
  • Status changed from Closed to Reopened
  • Category set to Processing/QGIS

The ability to do open to many queries is extremely useful. The ability to return one table with all the records joined is also useful.

Imagine if one to one joins only worked as relations did. Now would that be as useful as the existone one to one join geoprocessing function? I personally think not. Thus I feel it is the same with the one to many joins.

I'd like many to many joins, aka full joins but I appreciate that would be technically complex to impliment.

#6 Updated by Giovanni Manghi about 2 years ago

  • Status changed from Reopened to Feedback
  • Category changed from Processing/QGIS to Relations

infobleep - wrote:

The ability to do open to many queries is extremely useful. The ability to return one table with all the records joined is also useful.

Imagine if one to one joins only worked as relations did. Now would that be as useful as the existone one to one join geoprocessing function? I personally think not. Thus I feel it is the same with the one to many joins.

I'd like many to many joins, aka full joins but I appreciate that would be technically complex to impliment.

am I missing something? don't we have 1:n and n:m relations since a long now?

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