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

问题

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)
return p1, p2, v

In the output each entry is listed twice, with the values of p1 and p2 being switched. Example:

BOB | Mary | Cat video
Mary| Bob  | Cat video

How can such duplicate entries combined into one?

回答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.

来源：https://stackoverflow.com/questions/41603136/how-can-duplicate-results-in-a-different-order-be-removed-in-a-cypher-response