How can duplicate results in a different order be removed in a Cypher response?

Question

I am trying to find all the videos which 2 people commonly liked using the following cypher query

MATCH (p1: person)-[:LIKED]->(v)<-[:LIKED]-(p2: person)
r         


        

Answer 1

Here is one way to prevent duplicate results:

MATCH (p1: person)-[:LIKED]->(v)<-[:LIKED]-(p2: person)
WHERE ID(p1) < ID(p2)
RETURN p1, p2, v;

This works by requiring p1 to have a lower native ID than p2.