Create Relationships in Neo4j

In Neo4j, relationships are used to connect nodes and describe the nature of the connection. Creating relationships is a fundamental operation in graph databases, allowing you to build rich, interconnected data models.

Syntax

To create a relationship in Neo4j, you use the CREATE clause, followed by a pattern that specifies the nodes and relationship to be created:

CREATE (node1)-[relationship:RELATIONSHIP_TYPE]->(node2)

Here, node1 and node2 are existing nodes in the graph, and relationship is an identifier for the new relationship. RELATIONSHIP_TYPE is a user-defined string that describes the type of relationship being created.

Example

Let's say we have the following nodes in our graph:

(:Person {name: "Alice"})
(:Movie {title: "The Matrix"})

We can create a relationship between these nodes using the following query:

MATCH (p:Person {name: "Alice"}), (m:Movie {title: "The Matrix"})
CREATE (p)-[:ACTED_IN]->(m)

In this example, we're creating a :ACTED_IN relationship between the Person node with name Alice and the Movie node with title The Matrix.

Output

After executing the query, you can verify that the relationship was created using the MATCH clause:

MATCH (p:Person {name: "Alice"})-[:ACTED_IN]->(m:Movie {title: "The Matrix"})
RETURN p, m

This should return both nodes, connected by the ACTED_IN relationship.

╒═══════════════════════════════════════════════════╕
│"p"                                                │
╞═══════════════════════════════════════════════════╡
│{"name":"Alice","_id":0}                           │
└───────────────────────────────────────────────────┘
╒═══════════════════════════════════════════════════╕
│"m"                                                │
╞═══════════════════════════════════════════════════╡
│{"title":"The Matrix","_id":2}                      │
└───────────────────────────────────────────────────┘

Explanation

The CREATE clause creates a directed relationship between the Person node and the Movie node, with the identifier ACTED_IN. This relationship describes the fact that the person Alice acted in the movie The Matrix.

Use

Creating relationships in Neo4j is an important operation when building graph databases. Relationships connect nodes and describe the nature of the connection, giving meaning to the data in the graph.

Important Points

• The CREATE clause is used to create relationships in Neo4j.
• Relationships are created between existing nodes in the graph.
• The syntax for creating relationships includes a pattern that describes the nodes and relationship to be created.
• Relationships are directed, and can have user-defined labels.
• Relationships in Neo4j can have properties, which describe the nature of the relationship.

Summary

Creating relationships is a fundamental operation in Neo4j, allowing you to build rich, interconnected data models. Relationships are created with the CREATE clause, and describe the nature of the connection between nodes. Relationships can be directed, labeled, and can have properties, making it easy to build complex, multi-dimensional graphs.