jamesngondo2013 / cypher

Exercise 8

Semantic Web and Linked Data - Exercise 8

Cypher

In this exercise we will look at the neo4j querying language Cypher.

Introduction

1. Cypher is a querying language for Neo4j. It's like SQL, but deals with graph data.

2. CREATE is the Cypher keyword for creating nodes and relationships.

Exercises

1. Run Neo4j and go to http://localhost:7474/browser/.

2. Create a node for each of the four provinces of Ireland.

   CREATE (Leinster:Province {name: 'Leinster'}),
          (Munster:Province {name: 'Munster'}),
          ...;

3. Create a node for every county in Ireland.

   CREATE (Galway:County {name: "Galway"}),
          (Dublin:County {name: "Dublin"}),
          ...;

4. Create a relationship called IN_PROVINCE_OF for each county and province.

   MATCH
     (county:County),(province:Province)
   WHERE
     county.name = 'Antrim'
     AND province.name = 'Ulster'
   CREATE
     (county)-[county_in:IN_PROVINCE_OF]->(province)
   RETURN
     county_in;

5. Create a relationship called NEIGHBOUR_OF for each county and neighbouring county. You will find a list of neighbours in the file neighbours.csv. Note the pairs are directional.

6. for every pair of neighbouring counties, there should be two NEIGHBOUR_OF relationships, each directed a different way. Write a Cypher query to check for pairs of counties that have only a single NEIGHBOUR_OF relationship between them.

Advanced exercises

1. Build an API using express to run the queries from the exercises.

Notes

• Intro to Cypher from the Neo4j developer site.

• What is Cypher? from the Neo4j manual.

• Neo4j website

• Neo4j online getting started course

• Neo4j manual