检查Neo4J中2个节点之间是否存在关系，如果没有，则创建具有随机ID的节点

Question

I have UserTypeA node and UserTypeB node and I want to connect them to a User node that will be used now only to include random ID. is it possible to check if a relationship exits between 2 nodes (to check if UserTypeA already has a user node that is connect to him) and if not, to create a new User node and set a random id for this node (is it even possible to set a random id?). Is there a way to do it in one query? (if a relationship not exist, create new User node and set a random id for it)

Thanks

Answer 1

You can do this very straightforward, almost converting your English into Cypher:

MATCH (a:User {name:"userA"}),(b:User {name:"userB"})
WHERE NOT (a)-[:KNOWS]-(b)
WITH a,b
CREATE (c:User {name:"userC",id:rand()})
CREATE (a)-[:KNOWS]->(c)
CREATE (b)-[:KNOWS]->(c);