MERGE

Create missing graph data

The MERGE clause ensures that an expected pattern exists in the graph, reconciling whether data was found, or needs to be created through sub-clauses ON CREATE and ON MATCH.

Reference: MERGE ON CREATE ON MATCH
Related: :help MATCH :help CREATE :help Cypher
MERGE (charlie:Person { name:'Charlie Sheen', age:10 })
RETURN charlie
Look for a person named Charlie Sheen, age 10. If not found, create such a person.