Neo4j,匹配关系WHERE AND

Question

您好我想尝试使用'WHERE AND'来匹配neo4j关系

我的示例relationiship是:'用户访问国家'

我这样创造它......

MATCH (c:Country{Name:Country}) MERGE (u:User{Email:Email,UserID: UserID}) MERGE (u)-[r:Visits]->(c)
//Countries are previously created and Users may or may not exist

然后我查询(This Works):

MATCH (u:User)-[r:Visits]->(c:Country) where c.Name='France' or c.Name='Spain' return u

结果:向我显示访问过西班牙或法国的所有用户,即使他们只访问过两个国家/地区之一.

但我想要做的是完全相同的查询,但使用'AND'代替'OR'.我可以让用户访问"法国"和"西班牙".

MATCH (u:User)-[r:Visits]->(c:Country) where c.Name='France' AND c.Name='Spain' return u

结果:找到0个节点和关系..

我能做什么？

Answer 1

在您的查询中,您匹配单个国家/地区节点,并说该节点的名称必须是France和必须的Spain.

你想要的是找到所有在法国和西班牙都有征服的用户.你可以通过几种方式去...

//match both countries against the same user and identify them separtely
//making two matches in a single query
MATCH (u:User)-[:VISITS]->(c1:Country), (u)-[:VISITS]->(c2:Country)
WHERE c1.name = "France"
AND c2.name = "Spain"
RETURN u.name

//match all users that have been to either and only return the one that have been to both
MATCH (u:User)-[r:VISITS]->(c:Country) 
WHERE (c.name IN [ "France", "Spain"])
WITH u, count(*) AS num
WHERE num = 2
RETURN u.name, num 

它认为头号更好,因为它更精确,可能更有效.