AnalyticDB:Create and use a graph analysis engine

Query all data

• Find all nodes that have the Person label.

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

  The following is the result:

                                          result_a                                         
  -----------------------------------------------------------------------------------------
   {"id": 844424930131969, "label": "Person", "properties": {"name": "Zhang San"}}::vertex
   {"id": 844424930131970, "label": "Person", "properties": {"name": "Li Si"}}::vertex
   {"id": 844424930131971, "label": "Person", "properties": {"name": "Wang Wu"}}::vertex
  (3 rows)

• Find all edges that have the EMPLOYED label.

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

  The following result is returned:

                                                              result_a                                                            
  --------------------------------------------------------------------------------------------------------------------------------
   {"id": 1407374883553281, "label": "EMPLOYED", "end_id": 1125899906842625, "start_id": 844424930131969, "properties": {}}::edge
   {"id": 1407374883553282, "label": "EMPLOYED", "end_id": 1125899906842626, "start_id": 844424930131970, "properties": {}}::edge
   {"id": 1407374883553283, "label": "EMPLOYED", "end_id": 1125899906842625, "start_id": 844424930131971, "properties": {}}::edge
  (3 rows)

Query partial data (filtered data)

When you perform pattern matching in a graph and need to return specific data, you can use the WHERE clause to filter the matched results based on conditions.

• Query 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);

  The following shows the result.

                                          result_a                                         
  -----------------------------------------------------------------------------------------
   {"id": 844424930131969, "label": "Person", "properties": {"name": "Zhang San"}}::vertex
   {"id": 844424930131971, "label": "Person", "properties": {"name": "Wang Wu"}}::vertex
  (2 rows)

• Query 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)

  The result is:

                                          result_a                                         
  -----------------------------------------------------------------------------------------
   {"id": 844424930131969, "label": "Person", "properties": {"name": "Zhang San"}}::vertex
  (1 row)

Remove labels

When a label on a node or an edge is no longer needed, you can use the REMOVE keyword to delete it.

Syntax

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

Example

Remove the gender label from Zhang San.

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

Delete nodes

You can use the DELETE keyword to delete nodes or edges.

Syntax

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

Example

Create a node named Zhao Liu, and then delete the node.

-- Create a node named Zhao Liu.
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 edges

First, add a node named 'Zhao Liu' and an edge to specify that Zhao Liu is employed by Company C. Then, delete the employment relationship. To delete the relationship, you can specify the person's name and the company's name in the WHERE clause.

-- Create a node named Zhao Liu and an EMPLOYED edge between Zhao Liu and Company C.
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 nodes and their edges

If a node has associated edges, you cannot directly delete the node. You must use the DETACH DELETE statement to delete both the node and its edges.

Syntax

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

Example

Create a node named Zhao Liu and an EMPLOYED edge between Zhao Liu and Company C. Then, delete the edge and the Zhao Liu node.

-- Create a node named Zhao Liu and an EMPLOYED edge between Zhao Liu and Company C.
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);