Neo4J and Cypher query

Question

I am new to Neo4j and Cypher query.My create query is like each Shop has 2 chillers which has 2 PLCs each which in turn has 2 sensors each.

The create is as below

Create(:SHOP{name:"Shop1"})-[:hasChiller]->(:CHILLER{name:"Chiller1"})
Create(:SHOP{name:"Shop1"})-[:hasChiller]->(:CHILLER{name:"Chiller2"})

Create(:SHOP{name:"Shop2"})-[:hasChiller]->(:CHILLER{name:"Chiller3"})
Create(:SHOP{name:"Shop2"})-[:hasChiller]->(:CHILLER{name:"Chiller4"})

Create(:CHILLER{name:"Chiller1"})-[:hasPLC]->(:PLC{name:"Plc1"})
Create(:CHILLER{name:"Chiller1"})-[:hasPLC]->(:PLC{name:"Plc2"})

Create(:CHILLER{name:"Chiller2"})-[:hasPLC]->(:PLC{name:"Plc3"})
Create(:CHILLER{name:"Chiller2"})-[:hasPLC]->(:PLC{name:"Plc4"})

Create(:CHILLER{name:"Chiller3"})-[:hasPLC]->(:PLC{name:"Plc5"})
Create(:CHILLER{name:"Chiller3"})-[:hasPLC]->(:PLC{name:"Plc6"})

Create(:CHILLER{name:"Chiller4"})-[:hasPLC]->(:PLC{name:"Plc7"})
Create(:CHILLER{name:"Chiller4"})-[:hasPLC]->(:PLC{name:"Plc8"})

Create(:PLC{name:"Plc1"})-[:hasSensor]->(:SENSOR{name:"Sensor1"})
Create(:PLC{name:"Plc1"})-[:hasSensor]->(:SENSOR{name:"Sensor2"})
Create(:PLC{name:"Plc2"})-[:hasSensor]->(:SENSOR{name:"Sensor3"})
Create(:PLC{name:"Plc2"})-[:hasSensor]->(:SENSOR{name:"Sensor4"})
Create(:PLC{name:"Plc3"})-[:hasSensor]->(:SENSOR{name:"Sensor5"})
Create(:PLC{name:"Plc3"})-[:hasSensor]->(:SENSOR{name:"Sensor6"})
Create(:PLC{name:"Plc4"})-[:hasSensor]->(:SENSOR{name:"Sensor7"})
Create(:PLC{name:"Plc4"})-[:hasSensor]->(:SENSOR{name:"Sensor8"})
Create(:PLC{name:"Plc5"})-[:hasSensor]->(:SENSOR{name:"Sensor9"})
Create(:PLC{name:"Plc5"})-[:hasSensor]->(:SENSOR{name:"Sensor10"})
Create(:PLC{name:"Plc6"})-[:hasSensor]->(:SENSOR{name:"Sensor11"})
Create(:PLC{name:"Plc6"})-[:hasSensor]->(:SENSOR{name:"Sensor12"})
Create(:PLC{name:"Plc7"})-[:hasSensor]->(:SENSOR{name:"Sensor13"})
Create(:PLC{name:"Plc7"})-[:hasSensor]->(:SENSOR{name:"Sensor14"})
Create(:PLC{name:"Plc8"})-[:hasSensor]->(:SENSOR{name:"Sensor15"})
Create(:PLC{name:"Plc8"})-[:hasSensor]->(:SENSOR{name:"Sensor16"})

However the Match to get the sensors under SHOP1

MATCH(s:SHOP{name:"Shop1"})-[:hasChiller]->(cc:CHILLER)-[:hasPLC]->(pp:PLC)-[:hasSensor]->(ss:SENSOR) return ss.name

returns nothing.Says no changes and no data.

I am trying this out on Neo4J sandbox environment.I did this based on the understanding i had using match clause in SQL SERVER GRAPH 2019 where this works.

Can anyone point out where i am going wrong?

cybersam cybersam · Accepted Answer · 2020-06-26T19:31:12

You are improperly creating multiple instances of the "same" node. You should create each node once, and then use its bound variable name later on when you need to create relationships involving that node.

Delete all your data and follow this pattern instead (you have to fill in the "..." parts):

CREATE
  (sh1:SHOP{name:"Shop1"}), (sh2:SHOP{name:"Shop1"}),
  (c1:CHILLER{name:"Chiller1"}), (c2:CHILLER{name:"Chiller2"}),(c3:CHILLER{name:"Chiller3"}), (c4:CHILLER{name:"Chiller4"}),
  (p1:PLC{name:"Plc1"}), ..., (p8:PLC{name:"Plc8"}),
  (se1:SENSOR{name:"Sensor1"}), ..., (se16:SENSOR{name:"Sensor16"}),

  (sh1)-[:hasChiller]->(c1), (sh1)-[:hasChiller]->(c2),
  ... // create remaining relationships using bound variable names for nodes

Neo4J and Cypher query

1 Answers