Neo4j:如何更好地编写此查询？

Question

我是 Neo4j 的新手。我试图做这个查询:

"Mati Gol would like to watch a new movie. therefore would like to get the following list of movies: Write a query that returns all movies that were LIKED by any person who is a FRIEND of the person with the name Mati Gol or is a FRIEND of a FRIEND of Mati Gol, excluding all movies WATCHED by Mati Gol."

我的查询是:

MATCH (a:person {name:"Moti Gol"})-[:WATCHED]->(b)
WITH collect(b) AS Already_Watched
MATCH (a:person {name:"Moti Gol"})-[:FRIEND*1..2]->(b)-[:LIKED]->(c) 
WITH collect(c) AS Friend_Liked
(movie:Friend_Liked) WHERE NOT (movie.name) IN Already_Watched 
RETURN movie.name

这个查询好吗？有人可以为我提供更好的写作吗？

Answer 1

您的查询有一些错误...首先，第一行没有 MATCH 语句。您正在匹配 (a:person {name:"Moti Gol"})两次并重新声明 a多变的。

执行相同查询的更简单直观的方法:

// get all the movies liked by friends or friends of friends of "Moti Gol"...
MATCH (a:person {name:"Moti Gol"})-[:FRIEND*1..2]->(b:person)-[:LIKED]->(c:movie)
// excluding all movies WATCHED by Mati Gol
WHERE NOT (a)-[:WATCHED]->(c)
// return the movies
RETURN c.name