CODEWITHSUNDEEP
neo4jcypher
Jens Mikkelsen
Jens Mikkelsen

Reputation: 2712

merge where alternative and multiple conditions

So as far as I can tell, it is not possible to use where in a merge statement. Then how do I do multiple conditions?

What I want to achieve, but cannot work:

MERGE (n:Node) 
WHERE n.key = "test1" OR n.key = "test2"
ON CREATE n.key = "test1"
return n

So how do I create an or condition on my merge statement? Or is there a better way to do it?

Upvotes: 3

Views: 2141

Answers (2)

Michael Hunger
Michael Hunger

Reputation: 41676

Not sure how you would deal with the condition that you already have two nodes, one with test1 and another one with test2 in your graph. You would have to merge the two nodes, e.g. also moving the relationships from test2 to test1.

In general I'd try something like this (like cybersam suggested):

OPTIONAL MATCH (n:Node { key: 'test2' })
SET n.key = 'test1'
MERGE (m:Node { key: "test1" })
RETURN m

Upvotes: 0

cybersam
cybersam

Reputation: 66999

It does not look like MERGE supports the WHERE clause. However, you can specify ONE test value per property; for example:

MERGE (n:Node {key:'test1'})
RETURN n;

In your case, since you want to test for multiple values per property, there is no way to do that with MERGE

Also, if I understand what you are trying to do, it does not look like MERGE was the right thing to use anyway. I think the following Cypher code should give you the results that you are looking for: 

MATCH (n:Node { key: "test1" })
RETURN n
UNION
OPTIONAL MATCH (n:Node { key: 'test2' })
SET n.key = 'test1'
RETURN n;

Upvotes: 3

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