Cypher Fundamentals-Creating Nodes

Cypher Fundamentals

MERGE (p:Person {name: 'Michael Cain'})

It creates a single node in the graph. Note that when you use MERGE to create a node, you must specify at least one property that will be the unique primary key for the node.

Verify that the node was created.

cypher  

MATCH (p:Person {name: 'Michael Cain'})
RETURN p

Executing multiple Cypher clauses

We can also chain multiple MERGE clauses together within a single Cypher code block.

cypher  

MERGE (p:Person {name: 'Katie Holmes'})
MERGE (m:Movie {title: 'The Dark Knight'})
RETURN p, m

This code creates two nodes, each with a primary key property. Because we have specified the variables p and m, we can use them in the code to return the created nodes.

Using CREATE instead of MERGE to create nodes

Cypher has a CREATE clause you can use for creating nodes. The benefit of using CREATE is that it does not look up the primary key before adding the node. You can use CREATE if you are sure your data is clean and you want greater speed during import. We use MERGE in this training because it eliminates duplication of nodes.

Check your understanding

1. Creating a node

Which Cypher keywords can you use to create nodes?

•  

  INSERT

•  

  ADD

•  

  CREATE

•  

  MERGE

2. Using MERGE

When using MERGE to create a node, what must you specify?（2，4）

•  

  The number of properties the node will have.

•  

  The label for the node.

•  

  The index to be used for the node.

•  

  The name and value for the property that will be the primary key for the node.

HINT

What two things are used to uniquely identify a node in the graph?

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