Conceot

• Nodes：基本节点
• labels： 类似于node的类型
• relationships：节点间的关系
• properties：节点的属性

Start

sandbox: https://neo4j.com/sandbox-v2/

docker: https://hub.docker.com/_/neo4j/

docker run -d --publish=7474:7474 --publish=7687:7687 --volume=$HOME/neo4j/data:/data neo4j

Migrate from relational database

Workbench export data to CSV

https://dzone.com/refcardz/from-relational-to-graph-a-developers-guide

load csv with headers from "file:///v3_user.csv" as row
create (n:User)
SET n = row

Basic grammar

() for node

[] for relation

{} for properties

• MATCH
• CREATE
• RETURN
• WITH: pipe the result

• CREATE (ee:Person { name: "Emil", from: "Sweden", klout: 99 })
  

• CREATE clause to create data

• () parenthesis to indicate a node

• ee:Person a variable 'ee' and label 'Person' for the new node

• {}brackets to add properties to the node

MATCH (ee:Person) WHERE ee.name = "Emil" RETURN ee;

• MATCHclause to specify a pattern of nodes and relationships

• (ee:Person)a single node pattern with label 'Person' which will assign matches to the variable 'ee'

• WHEREclause to constrain the results

• ee.name = "Emil"compares name property to the value "Emil"

• RETURNclause used to request particular results

MATCH (ee:Person)-[:KNOWS]-(friends) WHERE ee.name = "Emil" RETURN ee, friends

• MATCHclause to describe the pattern from known Nodes to found Nodes
• (ee)starts the pattern with a Person (qualified by WHERE)
• -[:KNOWS]-matches "KNOWS" relationships (in either direction)
• (friends)will be bound to Emil's friends

MATCH (js:Person)-[:KNOWS]-()-[:KNOWS]-(surfer)
WHERE js.name = "Johan" AND surfer.hobby = "surfing"
RETURN DISTINCT surfer

• ()empty parenthesis to ignore these nodes

• DISTINCTbecause more than one path will match the pattern

• surferwill contain Allison, a friend of a friend who surfs

显示语句执行过程 EXPLAIN或者PROFILE

PROFILE MATCH (js:Person)-[:KNOWS]-()-[:KNOWS]-(surfer)
WHERE js.name = "Johan" AND surfer.hobby = "surfing"
RETURN DISTINCT surfer

Query all nodes

MATCH (n)
RETURN n

delete nodes and its relationship

MATCH (emil:Person {name:"Emil Eifrem"})
OPTIONAL MATCH (emil)-[r]-()
DELETE emil,r

create nodes with constraints

CREATE CONSTRAINT ON (flight:Flight) ASSERT flight.code IS UNIQUE;

iterator path

6 hop

MATCH path = (london:City{name:'London'})-[:HAS_FLIGHT|FLYING_TO*0..6]->(melbourne:City{name:'Melbourne'}) RETURN path;

tutorial

https://neo4j.com/graphacademy/online-training/getting-started-graph-databases-using-neo4j/part-1/