如何在Neo4j中用Cypher表示此查询

Question

I'm having some problems for solving a query in my Neo4j DB. My DB stores info about users, songs and albums. A user can buy songs and albums and he can follow other users too.

I start from "Lisa" user. I want to find users who bought albums with same style than albums bought by Lisa but they aren't followed by Lisa (they would be recommended users for Lisa to follow them).

I think that query would be similar to this but I can't find the correct sintax to represent it.

    MATCH (me:User)-[:BOUGHT]->(a:Album)
    MATCH (other:User)-[:BOUGHT]->(a2:Album)
    WHERE NOT (me)-[:FOLLOWS]->(other) AND me.username="Lisa" 
    AND other.username <> "Lisa" AND a.style=a2.style
    RETURN other.username

Any help? Thanks a lot :)

Answer 1

Your query works fine with this dataset. I might be misunderstanding something - can you further specify the problem?

CREATE
  (u1:User {username: "Lisa"}),
  (u2:User {username: "Louis"}),
  (a1:Album {style: "rock"}),
  (a2:Album {style: "rock"}),
  (u1)-[:BOUGHT]->(a1),
  (u2)-[:BOUGHT]->(a2)

I added some cosmetic touches to your query:

MATCH (me:User {username: "Lisa"})-[:BOUGHT]->(a1:Album)
MATCH (other:User)-[:BOUGHT]->(a2:Album)
WHERE NOT (me)-[:FOLLOWS]->(other)
  AND other.username <> "Lisa"
  AND a1.style=a2.style
RETURN other.username

The result is:

╒══════════════╕
│other.username│
╞══════════════╡
│Louis         │
└──────────────┘