Cypher Fundamentals-Finding Relationships

Cypher Fundamentals

Reading Data from Neo4j

• Introduction to Cypher
• Retrieving Nodes
• Finding Relationships
• Traversing Relationships
• Finding Emil
• Filtering Queries
• Finding Specific Actors

Writing Data to Neo4j

• Creating Nodes
• Creating a Node
• Creating Relationships
• Creating a Relationship
• Updating Properties
• Adding Properties to a Movie
• Merge Processing
• Adding or Updating a Movie
• Deleting Data
• Deleting Emil

QUIZ

Finding Relationships

VideoTranscript

 

Finding relationships

OUR GOAL

As a movie fanatic
I would like to find movies for a particular actor
So that I can watch a movie this evening

In the previous lesson, we used the MATCH clause to find the node in our database that represented Tom Hanks.

cypher

 

Copy to ClipboardRun in Sandbox

MATCH (p:Person {name: 'Tom Hanks'})
RETURN p

We can extend the pattern in the MATCH clause to traverse through all relationships with a type of ACTED_IN to any node. Our domain model shows that the ACTED_IN relationship goes in an outgoing direction from the Person node so we can add the direction in our pattern. We often refer to this as a traversal.

cypher

Incomplete code

 

MATCH (p:Person {name: 'Tom Hanks'})-[:ACTED_IN]->()

Our data model dictates that the node at the other end of that relationship will be Movie node, so we don’t necessarily need to specify the :Movie label in the node - instead we will use the variable m.

cypher

 

Copy to ClipboardRun in Sandbox

MATCH (p:Person {name: 'Tom Hanks'})-[:ACTED_IN]->(m)
RETURN m.title

This code returns the titles of all moves that Tom Hanks acted in.

If our graph had different labels, for example Television and Movie nodes this query would have returned all Television and Movie nodes that Tom Hanks acted in. That is, if we had multiple types of nodes at the end of the ACTED_IN relationships in our graph, we could make sure that we only return movies.

cypher

 

Copy to ClipboardRun in Sandbox

MATCH (p:Person {name: 'Tom Hanks'})-[:ACTED_IN]->(m:Movie)
RETURN m.title

Because our graph only has Movie nodes that have incoming ACTED_IN relationships, this query returns the exact same results as the previous query.

Check your understanding

1. Specifying the relationship direction

Say we wrote our query above differently and started with the Movie node. Use the dropdown below to select the correct direction for the query.

Once you have selected your option, click the Check Results query button to continue.

cypher

 

MATCH (m:Movie)
-[:ACTED_IN]->
<-[:ACTED_IN]-
(p:Person)
RETURN m.title, p.name

2. Query using a pattern

Which MATCH clauses will return the names of the directors of the movie, The Matrix?

•  

  MATCH (m:Movie {title: 'The Matrix'})<-[:DIRECTED]-(p:Person) RETURN p.name

•  

  MATCH (m:Movie {title: 'The Matrix'})--(p:Person) RETURN p.name

•  

  MATCH (m:Movie {title: 'The Matrix'})<-[:DIRECTED]-(p) RETURN p.name

•  

  MATCH (m:Movie {title: 'The Matrix'})--(p:Director) RETURN p.name

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Retrieving Nodes

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Traversing Relationships