Question

假设我们有一个Neo4j图表，如（品牌） - [：from] - ＆gt;（发布）＆lt; - [：likes] - （人）。

如何返回具有最少数量的品牌帖子的密码查询，例如3.我希望这是可扩展的，而不依赖于特定的属性属性值。

因此，结果将返回至少3个Brand节点的实例，以及5个来自Post和15个来自Person。

我尝试过几件不同的事情：

1。）为每个品牌声明几个变量名称（不可扩展）

    Match (b:Brand)-[]->(p:Post)<-[]-(per:Person) 
    Match (b1:Brand)-[]->(p1:Post)<-[]-(per2:Person)
    Match (b2:Brand)-[]->(p2:Post)<-[]-(per3:Person)
    return b,b1,b2,p,p1,p2,per,per2,per3
    limit 30

这不起作用，因为它基本上与

返回相同

    Match (b:Brand)-[]->(p:Post)<-[]-(per:Person) 
    return b,p,per
    limit 30

2。）使用foreach some

    Match (b:Brand) WITH collect (distinct b) as bb 
    FOREACH (b in bb[0..3] | MATCH (b)-[]->(p:Post)<-[]-(per:Person)) 
    RETURN b, p, per LIMIT 40

这不起作用，因为你不能在Foreach调用中使用Match。

我知道如何执行此操作的唯一方法是声明where子句及其唯一的属性品牌名称值，这些值不可伸缩。它看起来像这样：

    Match (b:Brand)-[]->(p:Post)<-[]-(per:Person) 
    where b.brand = "b1" OR b.brand   ="b2" or b.brand = "b3"
    Return b,p,per  
    Limit 30

然而，上面仍然没有回复我想要的东西。

请帮忙。这是一个快速测试图表：

    Create (b1:Brand {brand:'b1'})
    Create (b2:Brand {brand:'b2'})
    Create (b3:Brand {brand:'b3'})
    Create (p1:Post {id: "001",message: "foo"})
    Create (p2:Post {id: "002",message: "bar"})
    Create (p3:Post {id: "003",message: "baz"})
    Create (p4:Post {id: "004",message: "raz"})
    Create (per1:Person {id: "001",name: "foo"})
    Create (per2:Person {id: "002",name: "foo"})
    Create (per3:Person {id: "003",name: "foo"})
    Create (per4:Person {id: "004",name: "foo"})
    Create (per5:Person {id: "005",name: "foo"})
    Create (per6:Person {id: "006",name: "foo"})
    Create (per7:Person {id: "007",name: "foo"})
    Merge (b1)-[:FROM]->(p1)       
    Merge (b1)-[:FROM]->(p2)
    Merge (b2)-[:FROM]->(p3)
    Merge (b3)-[:FROM]->(p4)
    Merge (per1)-[:LIKES]->(p1)
    Merge (per1)-[:LIKES]->(p2)
    Merge (per1)-[:LIKES]->(p3)
    Merge (per2)-[:LIKES]->(p1)
    Merge (per2)-[:LIKES]->(p4)
    Merge (per3)-[:LIKES]->(p3)
    Merge (per4)-[:LIKES]->(p1)
    Merge (per5)-[:LIKES]->(p2)
    Merge (per6)-[:LIKES]->(p1)
    Merge (per6)-[:LIKES]->(p2)
    Merge (per6)-[:LIKES]->(p3)
    Merge (per6)-[:LIKES]->(p4)
    Merge (per7)-[:LIKES]->(p4)

Answer 1

您可以使用unwind代替foreach：

Match (b:Brand) WITH collect (distinct b) as bb 
UNWIND bb[0..3] as b
    MATCH (b)-[]->(p:Post)<-[]-(per:Person)
RETURN b, p, per LIMIT 40

或合并with和limit：

MATCH (b:Brand) WITH distinct b LIMIT 3
MATCH (b)-[]->(p:Post)<-[]-(per:Person)
RETURN b, p, per LIMIT 40

Cypher Query返回x特定类型节点的编号

1 个答案: