Functions

Predicate Functions

Predicates are boolean functions that return true or false for a given set of non-null input. They are most commonly used to filter out paths in the WHERE part of a query.

  • all()

  • any()

  • exists()

  • isEmpty()

In the Movie database, we want to find who is married and who is not:

MATCH (n:Person)
WHERE exists(n.name)
RETURN
   n.name AS name,
   exists((n)-[:MARRIED_TO]->()) AS is_married

Aggregating Functions

count()

The function count() returns the number of values or rows, and appears in two variants:

count(*)

returns the number of matching rows.

count(expr)

returns the number of non-null values returned by an expression.

Find the different relationships in the graph:

MATCH (n)-[r]->()
RETURN type(r), count(*)

MATCH (actor:Person)-[*2]-(friend_of_friend:Person)
WHERE actor.name = 'Tom Hanks'
RETURN count(DISTINCT friend_of_friend), count(friend_of_friend)

max

Find the year where the youngest person was born:

MATCH (n:Person)
RETURN max(n.born)

Mathematical Functions

  • abs()

  • ceil()

  • floor()

  • rand()

  • round()

String functions

  • left()

  • replace()

  • toLower()

  • toString()

  • toUpper()

  • trim()

Last change: Oct 30, 2023