I have a graph containing some nodes with :SubSystem
labels. I want to add a new node with a :Document
label and create relationships with each of the existing :SubSystem
nodes.
When I execute this statement:
MATCH (s:SubSystem)
CREATE (d:Document {title:'New Document'})
CREATE (d)-[:DEPICTS]->(s);
I was surprised when Neo4j created a new :Document
node for each :SubSystem
. I have 12 sub-systems, so I ended up with 12 new documents each related to one sub-system. I would have expected this behavior had I written:
MATCH (s:SubSystem)
CREATE (:Document {title:'New Document'})-[:DEPICTS]->(s);
But I was expecting that separating the CREATE
clauses would create 1 document then create relationships between that document and each of the sub-systems.
Can someone explain why this doesn't work as I was expecting.
EDIT:
I found a solution. This statement does what I wanted, but I still think my original attempt should have worked.
CREATE (d:Document {title:'New Document'})
WITH d MATCH (s:SubSystem) CREATE (d)-[:DEPICTS]->(s);
A MATCH
clause generates one or more result rows (or aborts the query if no results are found). A subsequent read/write clause would be executed once per row . Rearranging the order of the clauses, as you did, is one way to work around that (when possible).
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.