Question

当我运行下面的查询时查询1正在生成结果，返回所有文档的文档的所有类别标签。请注意，文档可以有多个类别，因此可以随时收集它们。

START doc = node:entities(type = "document-link")
MATCH  category-[:category]-doc<-[:`document-link`]-id
RETURN 
  doc.title    as title,
  COLLECT(COALESCE(category.category, "")) as categories

查询2正在为所有文档生成文档的结果返回语言。文档只能有一种语言类型。

START  doc = node:entities(type = "document-link")
MATCH  lan-[:language]-doc<-[:`document-link`]-id
RETURN 
  doc.title    as title,
  lan.language as language

查询3是1和2的连接产生空结果。有人可以突出我做错了吗？

START  doc = node:entities(type = "document-link")
MATCH  category-[:category]-lan-[:language]-doc<-[:`document-link`]-id
RETURN 
doc.title    as title,
lan.language as language,
COLLECT(COALESCE(category.category, "")) as categories

Answer 1

在您的第三个查询中，您匹配类别和语言之间的关系，您在前2个查询中不会这样做。怎么样：

START  doc = node:entities(type = "document-link")
MATCH category-[:category]-doc<-[:`document-link`]-id
MATCH doc-[:language]-lan
RETURN 
doc.title    as title,
lan.language as language,
COLLECT(COALESCE(category.category, "")) as categories

Neo4J查询加入多个匹配以返回结果

1 个答案: