Description of the three flavours of MERGE

gistfile1.txt

= Merge Examples =
 
:neo4j-version: 2.0.0-RC1
:author: Andrés Taylor
:twitter: @andres_taylor
:tags: domain:example
 
//setup
[source,cypher]
----
CREATE (a:Label {name:'A'}), (b:Label {name:'B'}), (c:Label {name:'C'})
RETURN a,b,c
----
 
This is the start data:
 
// graph
 
//table
 
Now we run this query
 
//output
[source,cypher]
----
MERGE (a:Label {name:'A'})
MERGE (a)-[:KNOWS]->(b:Label {name:'B'})
RETURN a,b
----
 
The graph now looks like:
 
//graph
 
Next, we run the other variant of MERGE, one where both ends are bound:

Now we run this query
 
//output
[source,cypher]
----
MERGE (a:Label {name:'A'})
MERGE (c:Label {name:'C'})
MERGE (a)-[:KNOWS]->(c)
RETURN a, c
----


Finally, the graph now looks like:
 
//graph