Neo4j, Match Relationship WHERE AND
Hello I am trying to map neo4j relationships using 'WHERE AND'
My example relationship: "User visits a country"
I create it like this ...
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
Then I request (This Works):
MATCH (u:User)-[r:Visits]->(c:Country) where c.Name='France' or c.Name='Spain' return u
Result: Shows all users who visited Spain or France, even if they only visited one of the two countries.
BUT what I am trying to do is the same exact query, but with "AND" instead of "OR". In which I can get users who have visited both "France" and "Spain".
MATCH (u:User)-[r:Visits]->(c:Country) where c.Name='France' AND c.Name='Spain' return u
Result: found 0 nodes and found links.
What can I do?
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In your request, you match the individual country of the node and state that the name of that node should be France
and should be Spain
.
What you want is to find all users who have outplayed France and Spain. There are several ways you can go ...
//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
He thinks number one is better as it is more accurate and probably more efficient.
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What's wrong with your request
MATCH (u:User)-[r:Visits]->(c:Country)
where c.Name='France'
AND c.Name='Spain'
return u
This will always return no rows because you are trying to check two values for the same node property.
Decision
MATCH (c1:Country)<-[r:Visits]-(u:user)-[r1:Visits]->(c2:Country)
WHERE c1.name = 'France' AND c2.name = 'Spain'
RETURN u.name;
This will give you back what you need.
Here is one short and helpful Neo4j reference document: http://neo4j.com/docs/2.1.2/cypher-refcard/
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