neo4j change relationship target from one node to another

Question

Assume I have this model in neo4j:

          (n2) -> (n3)-> (n9)
           /\
           |
   (n4)<-(n1)->(n5)->(n6)
    |            |
    \/           \/ 
    (n7)         (n8)

I need a cypher to change relationship between (n1) and (n2) to (n1) and (n6), like this:

                     (n2) -> (n3)-> (n9)
                      /\
                      |
   (n4)<-(n1)->(n5)->(n6)
    |            |
    \/           \/ 
    (n7)         (n8)

Answer 1

For those without APOC, Here is how to copy the relationship

MATCH (n1)-[r1:foo]->(n2),(n6)
WHERE n1.id = 1 AND n2.id = 2 and n6.id = 6
CREATE (n2)-[r2:foo]->(n6)
SET r2=r1
DELETE r1

Answer 2

If you have APOC Procedures installed, you can use a graph refactoring procedure to change the end point of a relationship. You'll need a match query to get the relationship, and the new start node, then use:

call apoc.refactor.from(rel, newStartNode)