Neo4j中基于Where条件的数据插入

Question

我想要基于其他lebel/collection插入数据。我有两个lebel/collection ( unit，user )，它们之间有一个关系(Business)，我想根据它们之间的关系将数据插入unit。我的密码查询如下：

MATCH (u:Units)<-[:Business]-(s:Users)
WHERE s.id = 'some-user-id'

WITH count(u) as numOfUnit  

// return number of units connected with user
// if numOfUnit is smaller then 2 
// insert/merge new data into Units lebel/collection 
// with relation between them

MERGE ( bu:Units {name:'some-name-01', info:'some-info-01' })
WHERE numOfUnit < 2
ON CREATE SET
  bu.id = '${uuid()}',
  bu.created = '${moment().toISOString()}'
ON MATCH SET
  bu.updated = '${moment().toISOString()}'

WITH bu as bu 

MATCH ( bs:Users {id: 'some-user-id' })
MERGE (bs)-[r:Business]-(bu)

RETURN properties(bu)   

在运行上面的查询后，它显示了以下错误：

 { Neo4jError: Invalid input 'H': expected 'i/I' (line 10, column 18 
    (offset: 377))
        "       ON CREATE SET"
        ^
           at Neo4jError.Error (native)
           at new Neo4jError (../../../../node_modules/neo4j-driver/lib/v1/error.js:76:132)
           at newError (../../../../node_modules/neo4j-driver/lib/v1/error.js:66:10)
           at Connection._handleMessage (../../../../node_modules/neo4j-driver/lib/v1/internal/connector.js:355:56)
           at Dechunker.Connection._dechunker.onmessage (../../../../node_modules/neo4j-driver/lib/v1/internal/connector.js:286:12)
           at Dechunker._onHeader (../../../../node_modules/neo4j-driver/lib/v1/internal/chunking.js:246:14)
           at Dechunker.AWAITING_CHUNK (../../../../node_modules/neo4j-driver/lib/v1/internal/chunking.js:199:21)
           at Dechunker.write (../../../../node_modules/neo4j-driver/lib/v1/internal/chunking.js:257:28)
           at NodeChannel.self._ch.onmessage (../../../../node_modules/neo4j-driver/lib/v1/internal/connector.js:259:27)
           at TLSSocket.<anonymous> (../../../../node_modules/neo4j-driver/lib/v1/internal/ch-node.js:308:16)
       code: 'Neo.ClientError.Statement.SyntaxError',
       name: 'Neo4jError' }

Answer 1

“关于哪里的文档”条款说：

，其中在MATCH或可选MATCH子句中向模式添加约束，或者使用子句过滤的结果。

也就是说：WHERE不能与MERGE一起使用。

正如注释中所述，您的查询应该可以将WHERE条件放在WITH子句之后，因为您可以使用WHERE过滤WITH的结果。

MATCH (u:Units)<-[:Business]-(s:Users)
WHERE s.id = 'some-user-id'

WITH count(u) as numOfUnit  
WHERE numOfUnit < 2

MERGE ( bu:Units {name:'some-name-01', info:'some-info-01' })
ON CREATE SET
    bu.id = '${uuid()}',
    bu.created = '${moment().toISOString()}'
ON MATCH SET
    bu.updated = '${moment().toISOString()}'

WITH bu as bu 

MATCH ( bs:Users {id: 'some-user-id' })
MERGE (bs)-[r:Business]-(bu)

RETURN properties(bu)