The document summarizes the key design decisions and features of Cypher, the graph query language for Neo4j. It discusses how Cypher uses pattern matching to query graph structures, supports directed and undirected relationships, variable length paths, optional relationships, and mutating operations like create, update, delete nodes and relationships. Examples are provided to demonstrate how to create a graph of ninja turtles and their relationships, update properties, and use Cypher to relate nodes and mutate the graph.

1. Cypher Query Language
Chicago Graph Database Meet-Up
Max De Marzi

2. What is Cypher?
• Graph Query Language for Neo4j
• Aims to make querying simple

3. Design Decisions
Pattern matching
A
B C

4. Design Decisions
Pattern matching

5. Design Decisions
Pattern matching

6. Design Decisions
Pattern matching

7. Design Decisions
Pattern matching

8. Design Decisions
ASCII-art patterns
() --> ()

9. Design Decisions
Directed relationship
A B
(A) --> (B)

10. Design Decisions
Undirected relationship
A B
(A) -- (B)

11. Design Decisions
specific relationships
LOVES
A B
A -[:LOVES]-> B

12. Design Decisions
Joined paths
A B C
A --> B --> C

13. Design Decisions
multiple paths
A
B C
A --> B --> C, A --> C
A --> B --> C <-- A

14. Design Decisions
Variable length paths
A B
A B
A B
...
A -[*]-> B

15. Design Decisions
Optional relationships
A B
A -[?]-> B

16. Mutating Cypher
New in Neo4j 1.8

17. Create Nodes
CREATE turtle1 = {name : 'Donatello'},
turtle2 = {name : ‘Michelangelo'}, Cypher
turtle3 = {name : ‘Raphael'},
turtle4 = {name : ‘Leonardo'}
The Ninja Turtles

18. Create Relationships
START t1 = node(1), t2 = node(2),
t3 = node(3), t4 = node(4)
CREATE s = {name: ‘Splinter’ },
t1-[r:DISCIPLE]->s,
Cypher
t2-[r:DISCIPLE]->s,
t3-[r:DISCIPLE]->s,
t4-[r:DISCIPLE]->s
The Ninja Turtles
are disciples of
Splinter

19. Delete Nodes
START s = node:nodes(name = ‘Shredder’)
DELETE s Cypher
Shredder is defeated

20. Update Properties
START t1 = node(0), t2 = node(2)
SET t1.weapon = ‘Bo Staff’, t2.hungry = ‘Yes’ Cypher
Donatello uses the Bo Staff
Michelangelo is always hungry

21. Delete Properties
START t2 = node(2)
DELETE t2.hungry Cypher
Michelangelo nom nom nom

22. Using Relate
START turtles = node(1,2,3,4)
RELATE turtles-[r:LOVE]->pizza Cypher
The Ninja Turtles
love pizza
A pizza node and 4
relationships are
created

23. Using Relate again
START turtles = node(1,2,3,4)
RELATE turtles-[r:LOVE]-(pizza Cypher
{name:’Supreme’})
The Ninja Turtles
love pizza
A pizza node with
name “Supreme”
and 4 relationships
are created

24. Questions?
maxdemarzi.com