CODEWITHSUNDEEP
neo4jcypher
v4gil
v4gil

Reputation: 911

neo4j MERGE, SET, CASE

I'm trying to do a tricky query. I need to check to see if a relationship exists;

The property can be go negative.

Here's essentially what I'm going for, though this format won't work because you can't have a WITH statement after a MERGE:

MATCH (n1:Type1 {id:{id1}), (n2:Type2 {id: {id2}) 
MERGE (n1)-[r:RELATIONSHIP]->(n2) WITH CASE 
WHEN r.prop + {val} < 0 THEN 0 
ELSE r.prop + {val} END as prop 
ON CREATE SET r.prop = prop
ON MATCH SET r.prop = prop

This is how it would look it two parts, though I'd like to not have to query twice:

MATCH (n1:Type1 {id:{id1}), (n2:Type2 {id: {id2}) 
MERGE (n1)-[r:RELATIONSHIP]->(n2)
ON CREATE SET r.prop = 0

MATCH (n1:Type1 {id:{id1})-[r:RELATIONSHIP]->n2:Type2 {id: {id2})
WITH r, CASE 
WHEN r.prop + {val} < 0 THEN 0 
ELSE r.prop + {val} END as prop
SET r.prop = prop

Upvotes: 2

Views: 3470

Answers (2)

v4gil
v4gil

Reputation: 911

MATCH (n1:Type1 {id:{id1}), (n2:Type2 {id: {id2}) 
MERGE (n1)-[r:RELATIONSHIP]->(n2)
ON CREATE SET r.prop = 
CASE
    WHEN {val} < 0 THEN 0
    ELSE {val}
    END
ON MATCH SET r.prop = 
CASE 
   WHEN r.prop + {val} < 0 
   THEN 0 
   ELSE r.prop + {val} 
   END

Upvotes: 1

Christophe Willemsen
Christophe Willemsen

Reputation: 20175

I think this query should do the trick :

MATCH (n1:Type1 {id:{id1}), (n2:Type2 {id: {id2}) 
MERGE (n1)-[r:RELATIONSHIP]->(n2)
ON CREATE SET r.prop = 0
ON MATCH SET r.prop = 
CASE r.prop 
   WHEN r.prop + {val} < 0 
   THEN 0 
   ELSE r.prop + {val} 
   END

Upvotes: 1

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