Getting all of combinations of features found on two layers using QGIS

Question

This is a problem that seems like it should be simple, but it's a little difficult to explain. I have two polygon layers, each with a few hundred features (specifically the districts of England and the constituencies of England). What I want is to produce a third polygon layer, which would take in all of the combinations of districts and constituencies.
See the example below for a much simpler version, the first layer has features 1 and 2, the second layer has features 3 and 4. In this case you would want to get four features out -the intersection of 1 from the first layer and 3 from the second, 1 from the first and 4 from the second, 2 from the first and 3 from the second, 2 from the first and 4 from the second.
Is this possible, and is there a more elegant way of phrasing this that I'm not seeing?

Kadir Şahbaz · Accepted Answer

You can use Intersection tool in "Processing Toolbox Ctrl+Alt+T > Vector overlay" for this.
For example, I have two layers as below:

After using Intersection tool, you get a new layer:

And using "Field Calculator" you can make a new field. Expression: id1 + ',' + id2

Result:

Getting all of combinations of features found on two layers using QGIS

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