AnalyticDB:Create and use a graph analysis engine

What is Cypher?

Cypher is an open source declarative graph query language from the openCypher project. It uses a visual, pattern-based syntax that mirrors the structure of a graph — parentheses for nodes, brackets for relationships, and arrows for direction — making it intuitive for developers already familiar with SQL.

MATCH (n:nodes)-[r:ARE_CONNECTED_TO]->(o:otherNodes)
RETURN n, r, o

In this pattern, (n:nodes) is a node with the label nodes (aliased as n), [r:ARE_CONNECTED_TO] is a directed relationship of type ARE_CONNECTED_TO (aliased as r), and (o:otherNodes) is the target node with the label otherNodes (aliased as o). The query returns all source nodes, target nodes, and their relationships that match this pattern.

Node syntax

Nodes are represented with parentheses ().

Relationship syntax

Relationships are represented with hyphens --. Add square brackets [] to include a variable, type, or properties. Add > for direction.

Pattern syntax

Combine node and relationship syntax to express rich graph patterns. For example:

(city_from:City {province: 'Zhejiang'})-[:NEXT_TO]-(city_next:City {province: 'Jiangsu'})

This pattern matches pairs of adjacent cities where one is in Zhejiang province and the other is in Jiangsu province, connected by an undirected NEXT_TO relationship.

Query all nodes or edges

Find all nodes with the Person label:

SELECT * FROM cypher('relation', $$
  MATCH (m:Person)
  RETURN m
$$) AS (result_a agtype);

Result:

Find all edges with the EMPLOYED label:

SELECT * FROM cypher('relation', $$
  MATCH (:Person)-[r:EMPLOYED]->(:Company)
  RETURN r
$$) AS (result_a agtype);

Result:

Filter results with WHERE

Add a WHERE clause to narrow results to specific nodes or edges.

Find all employees of Company A:

SELECT * FROM cypher('relation', $$
  MATCH (p:Person)-[:EMPLOYED]->(a:Company)
  WHERE a.name = 'Company A'
  RETURN p
$$) AS (result_a agtype);

Result:

Find Wang Wu's students:

SELECT * FROM cypher('relation', $$
  MATCH (p1:Person)-[:TEACHER]->(p2:Person)
  WHERE p1.name = 'Wang Wu'
  RETURN p2
$$) AS (result_a agtype);

Result:

Remove a property

Use REMOVE to delete a property from a node or edge.

SELECT * FROM cypher('<graph_name>', $$
  MATCH <pattern>
  REMOVE <property>
$$) AS (result_a agtype);

Remove the gender property from Zhang San:

SELECT * FROM cypher('relation', $$
  MATCH (p:Person {name: 'Zhang 3'})
  REMOVE p.gender
  RETURN p
$$) AS (result_a agtype);

Delete a node

Use DELETE to delete a node that has no edges.

SELECT * FROM cypher('<graph_name>', $$
  MATCH <pattern>
  DELETE <variable>
$$) AS (result_a agtype);

Create and then delete a node named Zhao Liu:

-- Create the node.
SELECT * FROM cypher('relation', $$
  CREATE (:Person {name: 'Zhao Liu'})
$$) AS (result_a agtype);

-- Delete the node.
SELECT * FROM cypher('relation', $$
  MATCH (p:Person {name: 'Zhao Liu'})
  DELETE p
$$) AS (result_a agtype);

Delete an edge

Match the edge by specifying both endpoints in WHERE, then delete it with DELETE.

Create Zhao Liu and an EMPLOYED edge to Company C, then delete the edge:

-- Create the node and edge.
SELECT * FROM cypher('relation', $$
  CREATE (ZhaoLiu:Person {name: 'Zhao Liu'})
  CREATE (ZhaoLiu)-[:EMPLOYED]->(:Company {name: 'Company C'})
$$) AS (result_a agtype);

-- Delete the edge.
SELECT * FROM cypher('relation', $$
  MATCH (p:Person)-[r:EMPLOYED]->(c:Company)
  WHERE p.name = 'Zhao Liu' AND c.name = 'Company C'
  DELETE r
$$) AS (result_a agtype);

Delete a node and its edges

When a node has associated edges, use DETACH DELETE to remove the node and all its edges.

SELECT * FROM cypher('<graph_name>', $$
  MATCH <pattern>
  DETACH DELETE <variable>
$$) AS (result_a agtype);

Create Zhao Liu with an EMPLOYED edge, then delete both:

-- Create the node and edge.
SELECT * FROM cypher('relation', $$
  CREATE (ZhaoLiu:Person {name: 'Zhao Liu'})
  CREATE (ZhaoLiu)-[:EMPLOYED]->(:Company {name: 'Company C'})
$$) AS (result_a agtype);

-- Delete the node and its edges.
SELECT * FROM cypher('relation', $$
  MATCH (p:Person {name: 'Zhao Liu'})
  DETACH DELETE p
$$) AS (result_a agtype);