Which relationship means one record in a table has exactly one matching record in the related table?

Relationship types with uncommon characters

Sometimes your database will have types with non-letter characters, or with spaces in them. Use ` (backtick) to quote these. To demonstrate this we can add an additional relationship between 'Charlie Sheen' and 'Rob Reiner':

Query

MATCH
  (charlie:Person {name: 'Charlie Sheen'}),
  (rob:Person {name: 'Rob Reiner'})
CREATE (rob)-[:`TYPE INCLUDING A SPACE`]->(charlie)

Which leads to the following graph:

Query

MATCH (n {name: 'Rob Reiner'})-[r:`TYPE INCLUDING A SPACE`]->()
RETURN type(r)

Returns a relationship type with spaces in it.

Multiple relationships

Relationships can be expressed by using multiple statements in the form of ()--(), or they can be strung together, like this:

Query

MATCH (charlie {name: 'Charlie Sheen'})-[:ACTED_IN]->(movie)<-[:DIRECTED]-(director)
RETURN movie.title, director.name

Returns the movie 'Charlie Sheen' acted in and its director.

Variable length relationships

Nodes that are a variable number of relationship->node hops away can be found using the following syntax: -[:TYPE*minHops..maxHops]->. minHops and maxHops are optional and default to 1 and infinity respectively. When no bounds are given the dots may be omitted. The dots may also be omitted when setting only one bound and this implies a fixed length pattern.

Query

MATCH (charlie {name: 'Charlie Sheen'})-[:ACTED_IN*1..3]-(movie:Movie)
RETURN movie.title

Returns all movies related to 'Charlie Sheen' by 1 to 3 hops.

Variable length relationships with multiple relationship types

Variable length relationships can be combined with multiple relationship types. In this case the *minHops..maxHops applies to all relationship types as well as any combination of them.

Query

MATCH (charlie {name: 'Charlie Sheen'})-[:ACTED_IN|DIRECTED*2]-(person:Person)
RETURN person.name

Returns all people related to 'Charlie Sheen' by 2 hops with any combination of the relationship types ACTED_IN and DIRECTED.

Relationship variable in variable length relationships

When the connection between two nodes is of variable length, the list of relationships comprising the connection can be returned using the following syntax:

Query

MATCH p = (actor {name: 'Charlie Sheen'})-[:ACTED_IN*2]-(co_actor)
RETURN relationships(p)

Returns a list of relationships.

Match with properties on a variable length path

A variable length relationship with properties defined on in it means that all relationships in the path must have the property set to the given value. In this query, there are two paths between 'Charlie Sheen' and his father 'Martin Sheen'. One of them includes a 'blocked' relationship and the other does not. In this case we first alter the original graph by using the following query to add BLOCKED and UNBLOCKED relationships:

Query

MATCH
  (charlie:Person {name: 'Charlie Sheen'}),
  (martin:Person {name: 'Martin Sheen'})
CREATE (charlie)-[:X {blocked: false}]->(:UNBLOCKED)<-[:X {blocked: false}]-(martin)
CREATE (charlie)-[:X {blocked: true}]->(:BLOCKED)<-[:X {blocked: false}]-(martin)

This means that we are starting out with the following graph:

Query

MATCH p = (charlie:Person)-[* {blocked:false}]-(martin:Person)
WHERE charlie.name = 'Charlie Sheen' AND martin.name = 'Martin Sheen'
RETURN p

Returns the paths between 'Charlie Sheen' and 'Martin Sheen' where all relationships have the blocked property set to false.

Zero length paths

Using variable length paths that have the lower bound zero means that two variables can point to the same node. If the path length between two nodes is zero, they are by definition the same node. Note that when matching zero length paths the result may contain a match even when matching on a relationship type not in use.

Query

MATCH (wallstreet:Movie {title: 'Wall Street'})-[*0..1]-(x)
RETURN x

Returns the movie itself as well as actors and directors one relationship away

Named paths

If you want to return or filter on a path in your pattern graph, you can a introduce a named path.

Query

MATCH p = (michael {name: 'Michael Douglas'})-->()
RETURN p

Returns the two paths starting from 'Michael Douglas'

Matching on a bound relationship

When your pattern contains a bound relationship, and that relationship pattern does not specify direction, Cypher will try to match the relationship in both directions.

Query

MATCH (a)-[r]-(b)
WHERE id(r) = 0
RETURN a, b

This returns the two connected nodes, once as the start node, and once as the end node

What is a relationship in which there is one record in one table that can have many matching records in another table?

In which relationship one record in a table is associated with?

What kind of relationship contains only one record of the first table and is related to only one record of a second table?

What is a one