OpenCypher Basics

Node

(p:Person {name: "Alice"})

Where

• p = variable
• Person = label
• {} = properties

Relationship

(direction matters)

(p)-[:KNOWS]->(q)

• Both p and q represent nodes.

READ: Match nodes

MATCH (p:Person)
RETURN p

READ: Filter nodes

MATCH (p:Person)
WHERE p.name = "Alice"
RETURN p

READ: Match relationship

MATCH (p:Person)-[:KNOWS]->(friend)
RETURN p, friend

READ: Pattern matching

MATCH (p:Person)-[:KNOWS]->(f:Person)-[:KNOWS]->(fof)
RETURN fof

WRITE: Create nodes

CREATE (p:Person {name: "Alice", age: 30})

WRITE: Create relationships

MATCH (a:Person {name: "Alice"}), (b:Person {name: "Bob"})
CREATE (a)-[:KNOWS]->(b)

MERGE

MERGE (p:Person {name: "Alice"})

• Creates if not exists
• Matches if exists

(a bit like UPSERT)

Updating data:

MATCH (p:Person {name: "Alice"})
SET p.age = 31

Remove property.

REMOVE p.age

DELETE node

MATCH (p:Person {name: "Alice"})
DELETE p

DELETE relationship?

MATCH (p:Person {name: "Alice"})
DETACH DELETE p

Aggregation

MATCH (p:Person)
RETURN count(p)

MATCH (p:Person)
RETURN p.country, count(*)

Variable-length paths

MATCH (p:Person)-[:KNOWS*1..3]->(other)
RETURN other

SQL to Cyper mental switch

• JOIN -> Pattern matching
• Tables -> Graph
• Rows -> Paths
• Foreign Key -> Relationships