cypher刪除關係數大於數的所有節點關係

Question

我的密碼有什麼問題。完整的描述在標題中。

match (p:P)<-[r:LINK]-(:G) 
with r, count(r) as num 
where num > 100 
delete r 

Answer 1

您骨料r計數r時，這意味着每一行都會有一個計數的準確1.

爲了解決這個問題，你應該爲聚合p：

match (p:P)<-[r:LINK]-(:G) 
with p, count(r) as num 
where num > 100 
match (p)<-[r:LINK]-(:G) 
delete r 

另一個選項是collect與列表的關係，unwind對於選定的關係：

match (p:P)<-[r:LINK]-(:G) 
with p, count(r) as num, collect(r) as rs 
where num > 100 
unwind rs as r 
delete r 

如果使用這種方法，你不妨忽略count(r)和檢查rs集合的大小：

match (p:P)<-[r:LINK]-(:G) 
with p, collect(r) as rs 
where size(rs) > 100 
unwind rs as r 
delete r