Deleting a relationship IF a condition is true?

Neo4j Graph Platform Cypher
1

Just discovered Graph and Neo4j a couple of days ago and I must say I really like what it has to offer. I'm still tinkering around still, and now I wonder how I would proceed with conditions inside queries.
In the below code, how would I delete the relationship in the same query if the quantity is set to 0?

I have a hard time understanding the syntax of the conditionals inside Cypher.

    result = session.run(
        f'MATCH (order:Order {{ ref: "SomeOrder" }})<-[rel:IN_ORDER]-(product:Product {{ name: "SomeProduct" }}) '
        f'SET rel += {{ quantity: 0 }} '
        f'WITH order '
        f'MATCH (order)<-[r:IN_ORDER]-(p:Product) '
        f'RETURN order, p.name, p.price * r.quantity AS total_unit_price '
    )
2

Hello! Welcome to the community. If that only thing your checking is the quantity on the relationship you can just do:

match(o:Order)<-[r:IN_ORDER]-(p:Product)
where r.quantity = 0
delete r
return o, p

That will check to see that the quantity is zero and if so delete the relationship.

3

Hello @andre.krosby1992 and welcome :slight_smile:

If there are a lot of relations to delete, the best way to delete is:

CALL apoc.periodic.iterate('MATCH (o:Order)<-[r:IN_ORDER]-(p:Product)
WHERE r.quantity = 0 RETURN r', 'DELETE r', {batchSize:1000})

Regards,
Cobra

4

Also you can reference this article if you're looking for more info on conditional Cypher execution:

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