Cypher Essentials

1. Introduction

Cypher is a declarative query language for graph databases, primarily used with Neo4j. It allows users to express complex graph patterns in a simple and readable manner. This lesson aims to provide essential knowledge about Cypher, including its syntax, key concepts, and best practices.

2. Key Concepts

• Nodes: The primary entities in a graph (e.g., people, products).
• Relationships: Connections between nodes that link them (e.g., friends, purchases).
• Properties: Attributes associated with nodes and relationships (e.g., name, age).
• Labels: A way to categorize nodes (e.g., Person, Product).

3. Query Syntax

Cypher syntax is designed for clarity and conciseness. Here's a basic structure:

MATCH (n:Person)-[r:FRIENDS_WITH]->(m:Person)
RETURN n.name, m.name
            

This query matches two nodes labeled as Person with a relationship FRIENDS_WITH and returns their names.

3.1 Creating Nodes and Relationships

CREATE (a:Person {name: 'Alice', age: 30}),
       (b:Person {name: 'Bob', age: 25}),
       (a)-[:FRIENDS_WITH]->(b)
            

3.2 Updating Nodes

MATCH (a:Person {name: 'Alice'})
SET a.age = 31
            

3.3 Deleting Nodes and Relationships

MATCH (a:Person {name: 'Bob'})
DELETE a
            

4. Best Practices

• Always use labels for clarity.
• Limit the number of results returned with LIMIT to improve performance.
• Utilize indexes for faster lookups on properties.
• Write readable queries using line breaks and indentation.

5. FAQ