15.5. Match

15.5.1. Related nodes
15.5.2. Outgoing relationships
15.5.3. Directed relationships and identifier
15.5.4. Match by relationship type
15.5.5. Match by relationship type and use an identifier
15.5.6. Relationship types with uncommon characters
15.5.7. Multiple relationships
15.5.8. Variable length relationships
15.5.9. Relationship identifier in variable length relationships
15.5.10. Zero length paths
15.5.11. Optional relationship
15.5.12. Optional typed and named relationship
15.5.13. Properties on optional elements
15.5.14. Complex matching
15.5.15. Shortest path
15.5.16. All shortest paths
15.5.17. Named path
15.5.18. Matching on a bound relationship

In the match part of a query, the pattern is described. The description of the pattern is made up of one or more paths, separated by commas.

Node identifiers can be used with or without surrounding parenthesis. These two match clauses are semantically identical:

MATCH (a)-->(b)

and

MATCH a-->b

All parts of the pattern must be directly or indirectly bound to a start point.

The optional relationship is a way to describe parts of the pattern that can evaluate to null if it can not be matched to the real graph. It’s the equivalent of SQL outer join - if Cypher finds one or more matches, they will be returned. If no matches are found, Cypher will return a null.

Optionality travels - if a part of the pattern can only be reached from a bound point through an optional relationship, that part is also optional. Also, named paths that contain optional parts are also optional - if any part of the path is null, the whole path is null.

In these example, b and p are all optional and can contain null:

START a=node(1) MATCH p = a-[?]->b

START a=node(1) MATCH p = a-[*?]->b

START a=node(1) MATCH p = a-[?]->x-->b

START a=node(1), x=node(100) MATCH p = shortestPath( a-[*?]->x )

Graph

cypher-match-graph.svg

15.5.1. Related nodes

The symbol -- means related to, without regard to type or direction.

Query

START n=node(3)
MATCH (n)--(x)
RETURN x

All nodes related to A are returned

Result

x
3 rows, 1 ms

Node[4]{name->"Bossman"}

Node[1]{name->"David"}

Node[5]{name->"Cesar"}


15.5.2. Outgoing relationships

When the direction of a relationship is interesting, it is shown by using --> or <--, like this:

Query

START n=node(3)
MATCH (n)-->(x)
RETURN x

All nodes that A has outgoing relationships to.

Result

x
2 rows, 0 ms

Node[4]{name->"Bossman"}

Node[5]{name->"Cesar"}


15.5.3. Directed relationships and identifier

If an identifier is needed, either for filtering on properties of the relationship, or to return the relationship, this is how you introduce the identifier.

Query

START n=node(3)
MATCH (n)-[r]->()
RETURN r

All outgoing relationships from node A.

Result

r
2 rows, 1 ms

:KNOWS[0] {}

:BLOCKS[1] {}


15.5.4. Match by relationship type

When you know the relationship type you want to match on, you can specify it by using a colon.

Query

START n=node(3)
MATCH (n)-[:BLOCKS]->(x)
RETURN x

All nodes that are BLOCKed by A.

Result

x
1 rows, 0 ms

Node[5]{name->"Cesar"}


15.5.5. Match by relationship type and use an identifier

If you both want to introduce an identifier to hold the relationship, and specify the relationship type you want, just add them both, like this.

Query

START n=node(3)
MATCH (n)-[r:BLOCKS]->()
RETURN r

All BLOCKS relationship going out from A.

Result

r
1 rows, 0 ms

:BLOCKS[1] {}


15.5.6. Relationship types with uncommon characters

Sometime your database will have types with non-letter characters, or with spaces in them. Use ` to escape these.

Query

START n=node(3)
MATCH (n)-[r:`TYPE WITH SPACE IN IT`]->()
RETURN r

This returns a relationship of a type with spaces in it.

Result

r
1 rows, 0 ms

:TYPE WITH SPACE IN IT[6] {}


15.5.7. Multiple relationships

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

Query

START a=node(3)
MATCH (a)-[:KNOWS]->(b)-[:KNOWS]->(c)
RETURN a,b,c

The three nodes in the path.

Result

abc
1 rows, 1 ms

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}

Node[2]{name->"Emil"}


15.5.8. Variable length relationships

Nodes that are variable number of relationship→node hops can be found using -[:TYPE*minHops..maxHops]->.

Query

START a=node(3), x=node(2, 4)
MATCH a-[:KNOWS*1..3]->x
RETURN a,x

Returns the start and end point, if there is a path between 1 and 3 relationships away

Result

ax
2 rows, 1 ms

Node[3]{name->"Anders"}

Node[2]{name->"Emil"}

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}


15.5.9. Relationship identifier in variable length relationships

When the connection between two nodes is of variable length, a relationship identifier becomes an iterable of relationships.

Query

START a=node(3), x=node(2, 4)
MATCH a-[r:KNOWS*1..3]->x
RETURN r

Returns the start and end point, if there is a path between 1 and 3 relationships away

Result

r
2 rows, 1 ms

List(Relationship[0], Relationship[3])

List(Relationship[0])


15.5.10. Zero length paths

When using variable length paths that have the lower bound zero, it means that two identifiers can point to the same node. If the distance between two nodes is zero, they are, by definition, the same node.

Query

START a=node(3)
MATCH p1=a-[:KNOWS*0..1]->b, p2=b-[:BLOCKS*0..1]->c
RETURN a,b,c, length(p1), length(p2)

This query will return four paths, some of them with length zero.

Result

abcLENGTH(p1)LENGTH(p2)
4 rows, 3 ms

Node[3]{name->"Anders"}

Node[3]{name->"Anders"}

Node[3]{name->"Anders"}

0

0

Node[3]{name->"Anders"}

Node[3]{name->"Anders"}

Node[5]{name->"Cesar"}

0

1

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}

Node[4]{name->"Bossman"}

1

0

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}

Node[1]{name->"David"}

1

1


15.5.11. Optional relationship

If a relationship is optional, it can be marked with a question mark. This similar to how a SQL outer join works, if the relationship is there, it is returned. If it’s not, null is returned in it’s place. Remember that anything hanging of an optional relation, is in turn optional, unless it is connected with a bound node some other path.

Query

START a=node(2)
MATCH a-[?]->x
RETURN a,x

A node, and null, since the node has no relationships.

Result

ax
1 rows, 0 ms

Node[2]{name->"Emil"}

<null>


15.5.12. Optional typed and named relationship

Just as with a normal relationship, you can decide which identifier it goes into, and what relationship type you need.

Query

START a=node(3)
MATCH a-[r?:LOVES]->()
RETURN a,r

A node, and null, since the node has no relationships.

Result

ar
1 rows, 0 ms

Node[3]{name->"Anders"}

<null>


15.5.13. Properties on optional elements

Returning a property from an optional element that is null will also return null.

Query

START a=node(2)
MATCH a-[?]->x
RETURN x, x.name

The element x (null in this query), and null as it’s name.

Result

xx.name
1 rows, 0 ms

<null>

<null>


15.5.14. Complex matching

Using Cypher, you can also express more complex patterns to match on, like a diamond shape pattern.

Query

START a=node(3)
MATCH (a)-[:KNOWS]->(b)-[:KNOWS]->(c), (a)-[:BLOCKS]-(d)-[:KNOWS]-(c)
RETURN a,b,c,d

The four nodes in the path.

Result

abcd
1 rows, 2 ms

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}

Node[2]{name->"Emil"}

Node[5]{name->"Cesar"}


15.5.15. Shortest path

Finding a single shortest path between two nodes is as easy as using the shortestPath-function, like this.

Query

START d=node(1), e=node(2)
MATCH p = shortestPath( d-[*..15]->e )
RETURN p

This means: find a single shortest path between two nodes, as long as the path is max 15 relationships long. Inside of the parenthesis you write a single link of a path - the starting node, the connecting relationship and the end node. Characteristics describing the relationship like relationship type, max hops and direction are all used when finding the shortest path. You can also mark the path as optional.

Result

p
1 rows, 1 ms

(1)--[KNOWS,2]-->(3)--[KNOWS,0]-->(4)--[KNOWS,3]-->(2)


15.5.16. All shortest paths

Finds all the shortest paths between two nodes.

Query

START d=node(1), e=node(2)
MATCH p = allShortestPaths( d-[*..15]->e )
RETURN p

This will find the two directed paths between David and Emil.

Result

p
2 rows, 0 ms

(1)--[KNOWS,2]-->(3)--[KNOWS,0]-->(4)--[KNOWS,3]-->(2)

(1)--[KNOWS,2]-->(3)--[BLOCKS,1]-->(5)--[KNOWS,4]-->(2)


15.5.17. Named path

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

Query

START a=node(3)
MATCH p = a-->b
RETURN p

The two paths starting from the first node.

Result

p
2 rows, 0 ms

(3)--[KNOWS,0]-->(4)

(3)--[BLOCKS,1]-->(5)


15.5.18. Matching on a bound relationship

When your pattern contains a bound relationship, and that relationship pattern doesn specify direction, Cypher will try to match the relationship where the connected nodes switch sides.

Query

START r=rel(0)
MATCH a-[r]-b
RETURN a,b

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

Result

ab
2 rows, 1 ms

Node[3]{name->"Anders"}

Node[4]{name->"Bossman"}

Node[4]{name->"Bossman"}

Node[3]{name->"Anders"}