Cypher

Cypher is the used query language for graph-oriented NoSQL databases, like Neo4j.

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How does it work?

A simple SQL query which returns all values of a table, like:

SELECT * FROM table

could be “translated” into Cypher, which would return all nodes:

MATCH (n) RETURN n

In Cypher, the n letter is a variable which can be given any name. In the example above, all nodes are selected and stored in n in the command MATCH (n). They are then returned as the query output in the command RETURN n.

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Examples

Below, are some examples using Cypher for common operations in any database:

• Creating a isolated node

CREATE (node)

• Creating a node in a label

CREATE (node: label)

• Adding properties to a label

CREATE (n: label :subLabel {property: 'Value'}) RETURN n

One could also add duplicate labels to a same node with different values. These nodes can be retrieved by either property.

CREATE (n: label :sublabel {property: 'FirstValue', property: 'SecondValue'}) RETURN n

• Querying with a WHERE filter

MATCH (n) WHERE n.property = 'Value' RETURN n

• Creating relationships between nodes

MATCH (p: label), (c: label)
WHERE p.property = 'Value' AND c.property = 'Value'
MERGE (p) - [r: Relationship] -> (c)
RETURN p, c, r

• Deleting all nodes

MATCH (n) DETACH DELETE n