Am 15.04.2014 um 18:53 schrieb Kevin Burton <[email protected]>:
> The documentation on MERGE gives the following example:
>
> MATCH (charlie:Person { name:'Charlie Sheen' }),(wallStreet:Movie {
> title:'Wall Street' })
> MERGE (charlie)-[r:ACTED_IN]->(wallStreet)
> RETURN r
>
> It states that "Charlie Sheen had already been marked as acting on Wall
> Street, so the existing relationship is found and returned. "
> My question is what if the nodes 'charlie' and 'wallstreet' exist but there
> is no 'ACTED_IN' relationship?
then it will be created
> Also to further complicate things say that Person has a constraint on 'name'
> to be unique and Movie has a constraint on 'title' to be unique. Since there
> is (in my scenario) no 'ACTED_IN' relationship MERGE fails to match but also
> because of the constraits all of the nodes cannot be created. So in this case
> will the RETURN r be null?
no,
MERGE for paths works with bound identifiers.
so if both charlie and wallStreet are bound it uses them and doesn't create a
new node, only if one is not bound it will create a new node, to create a new
sub-path.
>
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