Cypher

Introduction#

Cypher is the query language used by Neo4j. You use Cypher to perform tasks and matches against a Neo4j Graph.

Cypher is “inspired by SQL” and is designed to by intuitive in the way you describe the relationships, i.e. typically the drawing of the pattern will look similar to the Cypher representation of the pattern.

Creation

Create a node

CREATE (neo:Company) //create node with label 'Company'

CREATE (neo:Company {name: 'Neo4j', hq: 'San Mateo'}) //create node with properties

Create a relationship

CREATE (beginning_node)-[:edge_name{Attribute:1, Attribute:'two'}]->(ending_node)

Query Templates

Running neo4j locally, in the browser GUI (default: https://localhost:7474/browser/), you can run the following command to get a palette of queries.

:play query template

This helps you get started creating and merging nodes and relationships by typing queries.

Create an Edge

CREATE (beginning_node)-[:edge_name{Attribute:1, Attribute:'two'}]->(ending_node)

Deletion

Delete all nodes

MATCH (n) 
DETACH DELETE n

DETACH doesn’t work in older versions(less then 2.3), for previous versions use

MATCH (n)
OPTIONAL MATCH (n)-[r]-()
DELETE n, r

Delete all nodes of a specific label

MATCH (n:Book) 
DELETE n

Match (capture group) and link matched nodes

Match (node_name:node_type {}), (node_name_two:node_type_two {})
CREATE (node_name)-[::edge_name{}]->(node_name_two)

Update a Node

MATCH (n) 
WHERE n.some_attribute = "some identifier" 
SET n.other_attribute = "a new value"

Delete All Orphan Nodes

Orphan nodes/vertices are those lacking all relationships/edges.

MATCH (n)
WHERE NOT (n)--()
DELETE n