Delete a Relationship using Cypher in Neo4j - neo4j tutorial - graph database
How to Delete Relationship using Cypher in Neo4j?
- You can delete relationships in the same way as deleting nodes - by matching the relationship/s you want to delete.
- You can delete one or many relationships in one go. You can even delete all relationships in the database.
- First, as a memory refresher, here are the relationships that we created earlier:
- Let's delete the relationship of type RELEASED.
- There are several ways we could go about this. Let's look at three.
- The following statement is quite broad - it will delete all relationships of type RELEASED:
MATCH ()-[r:RELEASED]-()
DELETE r
- You could also be more specific and write something like this:
MATCH (:Artist)-[r:RELEASED]-(:Album)
DELETE r
- The above statement will match all Artist nodes that have a relationship type of RELEASED with an Album node.
- You could be even more specific and do something like this:
MATCH (:Artist {Name: "Strapping Young Lad"})-[r:RELEASED]-(:Album
{Name: "Heavy as a Really Heavy Thing"})
DELETE r
- Any of those statements will result in the RELEASED relationship being deleted. The graph will look like this:
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Deleting Nodes with Relationships Attached
- Nodes can't be deleted if they still have relationships attached to them.
- If we try to run the following statement:
MATCH (a:Artist {Name: "Strapping Young Lad"}) DELETE a
- We will get the following error:
- This is because that node has a relationship connected.
- One option is to delete all relationships, then delete the node.
- Another option is to use the DETACH DELETE clause. The DETACH DELETE clause lets you delete a node and all relationships connected to it.
- So we can change the above statement to this:
MATCH (a:Artist {Name: "Strapping Young Lad"}) DETACH DELETE a
- Running that statement will result in the following success message:
Delete the Whole Database
- You can take the DETACH DELETE a step further and delete the whole database.
- Simply remove any filtering criteria and it will delete all nodes and all relationships.
- Go ahead and execute the following statement:
MATCH (n) DETACH DELETE n