1. Index

1.1 Creating an Index

CREATE INDEX ON:label (node)
eg.
CREATE (Dhawan:player{name: "shikar Dhawan", YOB: 1995, POB: "Delhi"})
Following is a sample Cypher Query to create an index on the node Dhawan in Neo4j.
CREATE INDEX ON:player(Dhawan)

Creating an Index

1.2 Deleting an Index

Neo4j CQL provides a "DROP INDEX" command to drop an existing index of a Node or Relationshis property.
DROP INDEX ON:label(node)
Following is a sample Cypher Query to create an index on the node named “Dhawan” in Neo4j.
DROP INDEX ON:player(Dhawan)

Delete an Index

2. Create Unique Constraint

MATCH (root {name: "Dhawan"}) 
CREATE UNIQUE (root)-[:LOVES]-(someone) 
RETURN someone 

eg.

CREATE(Dhawan:player{id:001, name: "shikar Dhawan", YOB: 1995, POB: "Delhi"}) 
CREATE(Jonathan:player {id:002, name: "Jonathan Trott", YOB: 1981, POB: "CapeTown"}) 
CREATE(Sangakkara:player {id:003, name: "Kumar Sangakkara", YOB: 1977, POB: "Matale"}) 
CREATE(Rohit:player {id:004, name: "Rohit Sharma", YOB: 1987, POB: "Nagpur"}) 
CREATE(Virat:player {id:005, name: "Virat Kohli", YOB: 1988, POB: "Delhi"}) 

Then
CREATE CONSTRAINT ON (n:player) ASSERT n.id IS UNIQUE
Then, input:
CREATE (Jadeja:player {id:002, name: "Ravindra Jadeja", YOB: 1988, POB: "NavagamGhed"})
Error:

Constraint Error

3. Drop Unique

DROP CONSTRAINT ON (node:label) 
ASSERT node.id IS UNIQUE 

eg.
Following is a sample Cypher Query to remove the UNIQUE constraint on the property id.

DROP CONSTRAINT ON (n:player) 
ASSERT n.id IS UNIQUE 

Result:

Drop Constraint Result