Useful Queries in Neo4j

1. Create nodes with label Employee and Department
CREATE (emp:Employee{id:"1001",name:"Tom",dob:"01/10/1982"})
CREATE (dept:Department { deptno:10,dname:"Accounting",location:"Hyderabad" })

2. Create node and relationship
CREATE (emp:Employee{id:"1001"})-[:WORKS AT{since:"2 days"}]->(dept:Department { deptno:10}) 

3. Selection
MATCH (n) RETURN n : returns all nodes and relationships
MATCH (emp:Employee{id:"1001"}) RETURN emp : returns the nodes with id as 1001.
MATCH (emp:Employee) WHERE emp.id="1001" RETURN emp : returns the same result as previous query, but is not preferred ue to performance impacts

4. Limiting results
MATCH (n) RETURN n LIMIT 10

5. Deletion
MATCH(n) DELETE(n)

6. Delete nodes and relationships(A node having relationship can only be deleted if all the relationships associated with that node is deleted.)
MATCH (n) DETACH DELETE n

7. Return attribute names of a node
MATCH (n) RETURN keys(n)

8. Get attributes along with values
MATCH (n) RETURN properties(n)

9. Regular expressions
MATCH (emp:Employee) 
WHERE emp.id=~'\\d+'
RETURN (emp)

10. Get create timestamp of a node
Match (n) RETURN timestamp()

11. Find all nodes that have a relationship with the designated label, and RETURN selected properties of the nodes and the relationships
MATCH (n)-[r:WORKS_AT]->()
RETURN n,r.since

12. Return distinct in neo4j
MATCH (n1)-[r:WORKS_AT]->(n2)
RETURN DISTINCT r.since

13. Aggregation
MATCH (n1)-[r:WORKS_AT]->(n2)
RETURN r.since,COUNT(*)

14. Create-Update-Delete properties
Merge (emp:Employee{id:"1001"}) ON CREATE SET emp.city:"Kochi",emp.dob:"01/10/1982" ON MATCH  SET name:"Michael" REMOVE emp.id

15. Return any relationship
MATCH (n)--(m) RETURN n

16. Find count of relationship in both directions
MATCH (n)
RETURN n.name,size((n)-->()) as outcount, size((n)<--()) as incount

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