Intersect two traversals in ArangoDB

问题

I'm trying to understand how to intersect two results in ArangoDB and my scenario looks like this.

I can easily find users living in Spain, Island or Europe with the query:

FOR x IN 1..3 INBOUND "places/Europe" situedIn,livesIn 
FILTER IS_SAME_COLLECTION('users',x)
return x

What I want to understand is the best way to extend the search capabilities to include Profession:

Example:

• Return all Police in Spain (returns [A])
• Return all Police in Europe (returns [A])
• Return all Legal in Europe (returns [A,B])

Thankful for any help

回答1:

After some more searching the answer is INTERSECTION

FOR a IN INTERSECTION (

(FOR x IN 1..3 INBOUND "places/Europe" situedIn
   FOR p IN INBOUND x livesIn
   return p),

(FOR x IN 1..3 INBOUND "profession/Medical" specializes
   FOR p IN INBOUND x worksWith
   return p)

) RETURN a

回答2:

The _commonNeighbors function may be what you're looking for. It returns the intersection between two sets of vertices.

https://docs.arangodb.com/3.0.10/Manual/Graphs/GeneralGraphs/Functions.html#commonneighbors

来源：https://stackoverflow.com/questions/39979189/intersect-two-traversals-in-arangodb