Cypher §

#syntax/cypher

• Query Language for Neo4j
  • Query Docs https://neo4j.com/docs/cypher-manual/current/clauses/match/
• Case-sensitive SQL like syntax, but for Graphs
  • Nodes: ()
  • Relationships: []
  • Paths: (n)--(m) or ()-[r {name: $value}]->() or ()<-[]-()
  • Returns result in Graph or Tabular format

Patterns §

Pattern	Description
(n)-[r]->(m)	Bind to relation r
(n)-[*]->(m)	Variable length relationships
(n)-[*1..5]->(m)	Variable length path of 1-5 relationships
(n)-[*0..]->(m)	Recursive Relationship
(n)-[:KNOWS|:LOVES]-(m)	match Relationship Type using OR
(me:Me:User)	match multiple Labels using AND

• Supports Aliases in Return clause: MATCH(o:Org) RETURN o.name as OrgName
• Short Where Clause: MATCH (p:Person{name: 'Frank'}) RETURN p.name
• Avoid duplicates with RETURN DISTINCT
• Optional Match with OPTIONAL MATCH(o:Org)
• Similar to SQL joins, Cypher has *0..
• Negate Pattern with NOT EXISTS( (n)--(m) ) or isEmpty( (n)-->(m) )
• Remove Nodes WITHOUT Relationships MATCH(n) DELETE n
• Remove Nodes WITH Relationships MATCH(n) DETACH DELETE n
• Create or Update with MERGE (u:User{name:"fab"})
• Inequality Comparison with <>

Examples §

MATCH (o) RETURN o; // find pattern in graph
 
MATCH (o:Org) RETURN o; // find node label Org
 
// find all offices that are located in city
MATCH (o:Office)-[r:IS_LOCATED_IN]->(c:CITY) RETURN o, r, c;
// or
MATCH p = (:Office)-[:IS_LOCATED_IN]->(:CITY) RETURN p;
 
// find frank
MATCH (p:Person)
WHERE p.name = 'Frank'
RETURN p.name
 
// Regular Expression
MATCH (d:Dept)-->(o:Org)
WHERE d.name =~ 'Gra.*'
RETURN d.name, 
  collect(distinct o.name) as OrgNames // collect to list
 
// Starts with & Count
MATCH (d:Dept)
WHERE d.name STARTS WITH 'Gra'
RETURN d.name, count(*)
ORDER BY d.name DESC
SKIP 3 // skip first 3 entries
LIMIT 5 // limit to first 5 entries