Neo4j::cypher aggregation

Read first how aggregation works here: http://docs.neo4j.org/chunked/1.8/query-aggregation.html

Count

count is used to count the number of rows. count can be used in two forms — count() with no arguments which just counts the number of matching rows, and count(<identifier>), which counts the number of non-null values in . Notice that the count method is also available on path objects as well in the global context.

Count number of non null values in

Example, count my friends

node(1).outgoing(:friends).count 

Same as START v2=node(1) MATCH (v2)-[:friends]->(v1) RETURN count(v1)

Count matching rows

Use the global context version of count for counting number of nodes connected to one node.

Example:

ret node(1).outgoing, count

Same as START v1=node(1) MATCH (v1)-->(v2) RETURN v2,count(*)