Relationships

In this lesson, you will:

Learn how to create relationships based on data in a CSV file
Create ACTED_IN relationships between the Person and Movie nodes.

Creating relationships

The acted_in.csv file contains the following data:

movieId - the movieId property of the Movie node
person_tmdbId - the tmbdId property of the Person node
role - the role the person played in the movie

To create the ACTED_IN relationship, you will need to:

LOAD CSV data from the acted_in.csv file.
MATCH the relevant Person and Movie nodes.
Use MERGE to create the ACTED_IN relationship between the matched Person and Movie nodes.

Review the Cypher statement below, which creates the ACTED_IN relationships between the Person and Movie nodes.

cypher

LOAD CSV WITH HEADERS
FROM 'https://data.neo4j.com/importing-cypher/acted_in.csv' AS row
MATCH (p:Person {tmdbId: toInteger(row.person_tmdbId)})
MATCH (m:Movie {movieId: toInteger(row.movieId)})
MERGE (p)-[r:ACTED_IN]->(m)
SET r.role = row.role

Try to identify:

The 2 MATCH clauses that find the appropriate Person and Movie nodes using the movieId and person_tmdbId properties.
The MERGE clause that creates the ACTED_IN relationship between the matched p and m nodes
The SET clause that sets the role property of the ACTED_IN relationship r.

This approach of `MATCH`ing 2 nodes and `MERGE`ing a relationship between them is a typical Cypher pattern.

ACTED_IN relationship

Run the Cypher statement to create the ACTED_IN relationships.

cypher

LOAD CSV WITH HEADERS
FROM 'https://data.neo4j.com/importing-cypher/acted_in.csv' AS row
MATCH (p:Person {tmdbId: toInteger(row.person_tmdbId)})
MATCH (m:Movie {movieId: toInteger(row.movieId)})
MERGE (p)-[r:ACTED_IN]->(m)
SET r.role = row.role

To verify that you created the ACTED_IN relationships successfully, run the following Cypher statement to find people who acted in movies:

cypher

MATCH (p:Person)-[r:ACTED_IN]->(m:Movie) RETURN p, r, m LIMIT 25

Check Your Understanding

Creating relationships

Which Cypher clause would you use to create a relationship?

❏ LOAD
❏ MATCH
✓ MERGE
❏ SET

Hint

Relationships are created in the same way as creating nodes.

Solution

You would use MERGE to create a relationship. For example:

cypher

MERGE (startNode)-[:RELATIONSHIP]->(endNode)

Summary

In this lesson, you learned how to create relationships between nodes from data in a CSV file.

In the next lesson, you will create the DIRECTED relationship between the Person and Movie nodes

Importing CSV data into Neo4j

Importing Data

Creating Nodes, Properties, and Relationships

Data Types, Lists, and Labels

Importing data considerations

Relationships

Creating relationships

ACTED_IN relationship

Check Your Understanding

Creating relationships

Summary

Chatbot