问题
I have a query (below) that returns collections of nodes containing create dates. I want to sort the rows by newest create date. Some of the rows have one create date, other rows have several. As can be seen, the node "name4" should be first. What corrections should I make to my query? Thanks.
MATCH (node:node)
WITH node
ORDER BY node.created DESC
RETURN count(node.name) AS count, node.name, collect(node.created) AS created
count node.name created
3 "name1" [1410234609620,1410234606534,1410234506799]
1 "name2" [1410234434936]
1 "name3" [1410234454573]
2 "name4" [1410463902552,1410460561481]
1 "name5" [1410234485185]
2 "name6" [1410234548527,1410234525740]
回答1:
Assuming your timestamps are correctly ordered within your collections, you can take the first timestamp from each of the collections using HEAD([1, 2, 3]), which will return the first element of the collection. I've loaded this value into the timeSort property and used it as the ordering criteria.
MATCH (node:node)
WITH node
ORDER BY node.created DESC
WITH count(node.name) AS count, node.name as name, collect(node.created) AS created
WITH count, name, head(created) as timeSort, created
RETURN count, name, created
ORDER BY timeSort DESC
回答2:
This query first finds the max timestamp, x, for each name, and then sorts the results.
MATCH (node:node)
WITH node.name AS name, COLLECT(node.created) AS created
WITH name, created, REDUCE(t = 0, c IN created | CASE WHEN c > t THEN c ELSE t END) AS x
RETURN LENGTH(created) AS count, name, created
ORDER BY x DESC
来源：https://stackoverflow.com/questions/25796226/neo4j-cypher-sort-on-collections