Creating Relationship basis condition and limit

[pragyasood28]

Hi All,
I am trying to create a relationship between the below path where all nodes have a date property to other nodes present in my Graph DB with rest of the dates like '2021-05-01' , '2021-06-01' ,,'2021-07-01'etc. but the relationship should be created where every month date is connected to the next month date

I have written this query : Match (a:Storage),(b:Storage)
where b.date=a.date+duration('P1M')
create (a)-[r:impact]->(b)

This works fine and creates the relation between all nodes but I just want to create relation between the nodes shown in the picture to just their next month i.e in the picture date is '2021-04-01' (but it can be any date) so it should be connected to nodes with date '2021-05-01' only and not connected further to '2021-06-01'. I want to limit my relationship creation. Is it possible ? And how to achieve it .

This is the Output that I want

Thanks

[SamChalvet]

Hi, if the Storage node that you are trying to connect too already exists you should be able to do something like this:

MATCH (a:Storage)
MATCH (b:Storage {date: a.date+duration('P1M')})
MERGE (a)-[:IMPACT]->(b)
RETURN *

I hope that helps.

[pragyasood28]

Hi Sam,

I just tried this what you suggested so this is also creating the relationship between all nodes all dates basis 1 month gap like '2021-04-01' connected to '2021-05-01' and then to '2021-06-01' and so on till '2023-03-01' (max date in my DB). I am getting this

But I just want to stop the relationship creation after 1 relationship between '2021-04-01' and '2021-05-01' .

Can you suggest how to achieve this.

Thanks

[SamChalvet]

Ah I see.

Could this be solved then by limiting the a:Storage node that is returned based on the pattern like so:

MATCH ()-[:TRANSPORTED]->(a:Storage)
MATCH (b:Storage {date: a.date+duration('P1M')})
MERGE (a)-[:IMPACT]->(b)
RETURN *

That way your "a" node will always be one that has been TRANSPORTED.

[pragyasood28]

Thanks Sam, I can make use of your and Benoit's query. This was helpful.

[pragyasood28]

So I cannot create it by limiting a:Storage basis TRANSPORTED because the other month Storage nodes like '2021-06-01', '2021-07-01' etc also have TRANSPORTED relationship. Sorry, I didn't mention this before that those months are also separate paths with TRANSPORTED Relation that I have in my DB.

[Benoit_d]

One trouble is that in order to have only one relatioship "IMPACT" you should be able to query what you are creating, which is not possible within one query.
A simple solution, even if not the prettiest, would be to run a second query to delete the useless relationship in a chain:

MATCH (a:Storage)-[:IMPACT]->(b:Storage)-[rel:IMPACT*]->(c:Storage)
DELETE rel

[pragyasood28]

Thanks Beniot this is helpful.