"Invalid use of aggregating function in this context" in a SET query (Neo4j)

Question

I wonder why this is considered an invalid use of aggregate functions in Neo4j's Cypher:

MATCH (p:Project)-[:EMPLOYS]-(n:Person) SET p.youngest = MIN(n.age);

While the following is considered a valid use case:

MATCH (p:Project)-[:EMPLOYS]-(n:Person) RETURN p.name, MIN(n.age) AS youngest;

How should I rewrite the first query to make it valid?

score 10 · Accepted Answer · answered Dec 15 '14 at 22:27

10

As for "why" your original Cypher attempt does not work, and the answer by @mah does work: Cypher only permits aggregation functions to be used in WITH and RETURN clauses.

answered Dec 15 '14 at 22:27

cybersam

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why? What's the purpose of this implementation? – Monica Heddneck May 26 '16 at 07:04
@MonicaHeddneck You can ask the neo4j folks that, say on one of their [Slack channels](http://neo4j.com/blog/public-neo4j-users-slack-group/). – cybersam May 26 '16 at 18:04

score 9 · Answer 2 · edited Dec 15 '14 at 22:24

9

A slight change to the query makes it work:

MATCH (p:Project)-[:EMPLOYS]-(n:Person)
WITH p, MIN(n.age) AS min_age 
SET p.youngest = min_age;

edited Dec 15 '14 at 22:24

cybersam

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answered Dec 15 '14 at 19:33

retrography

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I fixed a slight typo in this answer, and reformatted the Cypher a bit. – cybersam Dec 15 '14 at 22:24

"Invalid use of aggregating function in this context" in a SET query (Neo4j)

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