Neo4j查询：应用多个WHERE条件无效

z0qdvdin 于 2022-11-05 发布在其他

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我有一个运行良好的查询。这给了我所有当前fuelPercentLeft超过50%的列车。

MATCH (t:Train) 
WITH t.trainId AS trainid, MAX(t.timestamp) AS maxTimeStamp
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) > 50
RETURN count(toInteger(m.value))

我只想用一个查询返回多个结果。例如，对于所有的列车，返回fuelPercentLeft大于50、Engine Temperature小于20、Lubricant Level小于10的所有列车。在上面的查询中，是否可以应用多个WHERE条件？我们是否可以执行以下操作？

MATCH (t:Train) 
WITH t.trainId AS trainid, MAX(t.timestamp) AS maxTimeStamp
CALL {
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) > 50
RETURN count(toInteger(m.value)) AS goodFuel
}
CALL {
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) < 50
RETURN count(toInteger(m.value)) AS badFuel
}
CALL {
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'engineTemp'}) 
WHERE toInteger(m.value) > 20
RETURN count(toInteger(m.value)) AS goodEngine
}
CALL {
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'lubricantLevel'}) 
WHERE toInteger(m.value) < 10
RETURN count(toInteger(m.value)) AS badLubricant
}
RETURN goodFuel, badFuel, goodEngine, badLubricant

我试过这个，但它不像预期的那样工作。要求是，一个单一的查询应该能够基于多个条件返回多个值。
请帮忙。谢谢！

neo4j

来源：https://stackoverflow.com/questions/72824744/neo4j-query-apply-multiple-where-conditions-not-working

2条答案

按热度按时间

ztyzrc3y1#

您可以在链中使用可选匹配：

MATCH (t:Train) 
WITH t.trainId AS trainid, MAX(t.timestamp) AS maxTimeStamp
OPTIONAL 
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) > 50
WITH trainid, maxTimeStamp, count(m) AS goodFuel
OPTIONAL 
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) < 50
WITH trainid, maxTimeStamp, goodFuel, count(m) AS badFuel
OPTIONAL 
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'engineTemp'}) 
WHERE toInteger(m.value) > 20
WITH trainid, maxTimeStamp, goodFuel, badFuel, count(m) AS goodEngine
OPTIONAL 
MATCH (n:Train{trainId: trainid, timestamp: maxTimeStamp})-[:HAS]->(m:Attributes{name:'lubricantLevel'}) 
WHERE toInteger(m.value) < 10
WITH trainid, maxTimeStamp, goodFuel, badFuel, goodEngine, count(m) AS badLubricant
RETURN trainid, maxTimeStamp, goodFuel, badFuel, goodEngine, badLubricant

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5sxhfpxr2#

您应用了错误的筛选器，对于trainId和maxTimeStamp，它们不是必需的，请尝试以下操作：

MATCH (n:Train)-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) > 50
WITH count(n) AS goodFuel
MATCH (n:Train)-[:HAS]->(m:Attributes{name:'fuelPercentLeft'}) 
WHERE toInteger(m.value) < 50
WITH goodFuel, count(n) AS badFuel
MATCH (n:Train)-[:HAS]->(m:Attributes{name:'engineTemp'}) 
WHERE toInteger(m.value) > 20
WITH goodFuel, badFuel, count(toInteger(m.value)) AS goodEngine
MATCH (n:Train)-[:HAS]->(m:Attributes{name:'lubricantLevel'}) 
WHERE toInteger(m.value) < 10
RETURN count(toInteger(m.value)) AS badLubricant, goodFuel, badFuel, goodEngine

赞(0）回复(0）举报 2022-11-05

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Neo4j查询：应用多个WHERE条件无效

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