CODEWITHSUNDEEP
neo4jcyphergraphql
Sukhinderpal Mann
Sukhinderpal Mann

Reputation: 884

How do I self reference within a table in Neo4j?

I have a few tables loaded up in Neo4j. I have gone through some tutorials and come up with this cypher query.

MATCH (n:car_detail)
RETURN COUNT(DISTINCT n.model_year), n.model, n.maker_name
ORDER BY COUNT(DISTINCT n.model_year) desc

This query gave me all the cars that were continued or discontinued. Logic being count one being discontinued and anything higher being continued.

My table car_detail has cars which were build in different years. I want to make a relationship saying for example "Audi A4 2011" - (:CONTINUED) -> "Audi A4 2015" - (:CONTINUED) -> "Audi A4 2016"

Upvotes: 0

Views: 185

Answers (2)

InverseFalcon
InverseFalcon

Reputation: 30397

So it sounds like you want to match to the model and make of the car, ordered by the model year ascending, and to create relationships between those nodes.

We can make use of APOC Procedures as a shortcut for creating the linked list through the ordered and collected nodes, you'll want to install this (with the appropriate version given your Neo4j version) to take advantage of this capability, as the pure cypher approach is quite ugly.

The query would look something like this:

MATCH (n:car_detail)
WITH n
ORDER BY n.model_year
WITH collect(n) as cars, n.model as model, n.maker_name as maker
WHERE size(cars) > 1
CALL apoc.nodes.link(cars, 'CONTINUED')
RETURN cars

The key here is that after we order the nodes, we aggregate the nodes with respect to the model and maker, which act as your grouping key (when aggregating, the non-aggregation variables become the grouping key for the aggregation). This means your ordered cars are going to be grouped per make and model, so all that's left is to use APOC to create the relationships linking the nodes in the list.

Upvotes: 1

Michael Hunger
Michael Hunger

Reputation: 41676

You can just find both cars with MATCH and then connect them:

e.g.

MATCH (c1:car_detail) 
where c1.model = 'Audi A4 2011' 
MATCH (c2:car_detail) 
where c2.model = 'Audi A4 2015' 
CREATE (c1)-[:CONTIUED]->(c2);

etc.

Upvotes: 0

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