apoc.cypher.runFirstColumnMany
函数

详细信息

语法

apoc.cypher.runFirstColumnMany(statement, params)

描述

执行给定的语句及其参数，并将结果的第一列收集为 LIST<ANY> 返回。

参数

名称

类型

描述

statement

STRING

要执行的 Cypher 查询语句。

params

MAP

给定 Cypher 查询所需的输入参数。

返回

LIST<ANY>

此函数在多线程环境下运行不安全。因此，它不支持并行运行时（Parallel runtime）。更多信息，请参阅 Cypher 手册 → 并行运行时。

在 Cypher 中使用动态标签

在 Cypher 中，无需使用 APOC 即可动态引用节点标签和关系类型。

用于动态创建、匹配和合并标签与类型的 Cypher 语法
CREATE (n1:$(label))-[r:$(type)]->(n2:$(label))
MERGE (n1:$(label))-[r:$(type)]->(n2:$(label))
MATCH (n1:$(label))-[r:$(type)]->(n2:$(label))

动态计算出的类型必须求值为 STRING 或 LIST<STRING>。更多信息，请参阅 Cypher 手册 → CREATE、MERGE、MATCH。

使用示例

本节中的示例基于以下示例图

CREATE (Keanu:Person {name:'Keanu Reeves', born:1964})
CREATE (TomH:Person {name:'Tom Hanks', born:1956})
CREATE (TomT:Person {name:'Tom Tykwer', born:1965})

CREATE (TheMatrix:Movie {title:'The Matrix', released:1999, tagline:'Welcome to the Real World'})
CREATE (TheMatrixReloaded:Movie {title:'The Matrix Reloaded', released:2003, tagline:'Free your mind'})
CREATE (TheMatrixRevolutions:Movie {title:'The Matrix Revolutions', released:2003, tagline:'Everything that has a beginning has an end'})
CREATE (SomethingsGottaGive:Movie {title:"Something's Gotta Give", released:2003})
CREATE (TheDevilsAdvocate:Movie {title:"The Devil's Advocate", released:1997, tagline:'Evil has its winning ways'})

CREATE (YouveGotMail:Movie {title:"You've Got Mail", released:1998, tagline:'At odds in life... in love on-line.'})
CREATE (SleeplessInSeattle:Movie {title:'Sleepless in Seattle', released:1993, tagline:'What if someone you never met, someone you never saw, someone you never knew was the only someone for you?'})
CREATE (ThatThingYouDo:Movie {title:'That Thing You Do', released:1996, tagline:'In every life there comes a time when that thing you dream becomes that thing you do'})
CREATE (CloudAtlas:Movie {title:'Cloud Atlas', released:2012, tagline:'Everything is connected'})

CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrix)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixReloaded)
CREATE (Keanu)-[:ACTED_IN {roles:['Neo']}]->(TheMatrixRevolutions)
CREATE (Keanu)-[:ACTED_IN {roles:['Julian Mercer']}]->(SomethingsGottaGive)
CREATE (Keanu)-[:ACTED_IN {roles:['Kevin Lomax']}]->(TheDevilsAdvocate)

CREATE (TomH)-[:ACTED_IN {roles:['Joe Fox']}]->(YouveGotMail)
CREATE (TomH)-[:ACTED_IN {roles:['Sam Baldwin']}]->(SleeplessInSeattle)
CREATE (TomH)-[:ACTED_IN {roles:['Mr. White']}]->(ThatThingYouDo)
CREATE (TomH)-[:ACTED_IN {roles:['Zachry', 'Dr. Henry Goose', 'Isaac Sachs', 'Dermot Hoggins']}]->(CloudAtlas)
CREATE (TomT)-[:DIRECTED]->(CloudAtlas);

此函数适用于执行包含动态节点标签或关系类型的 Cypher 语句，并返回单列的多行结果。不过，在某些情况下，不使用 APOC 也能实现相同功能（如果可能，以下示例将同时展示 Cypher 原生写法和 APOC 替代方案）。

例如，我们可以返回所有标签列表，以及具有这些标签的节点所使用的不同属性键集合。

apoc.cypher.runFirstColumnMany
CALL db.labels()
YIELD label
RETURN label,
       apoc.cypher.runFirstColumnMany(
          "MATCH (n:`" + label + "`)
           WITH DISTINCT keys(n) AS keys
           RETURN DISTINCT apoc.coll.sort(keys)",
          {}) AS keys;
MATCH 子句
CALL db.labels()
YIELD label
RETURN label, COLLECT {
    MATCH (n:$(label))
    WITH DISTINCT keys(n) AS keys
    RETURN DISTINCT apoc.coll.sort(keys)
};
结果
标签 (label) keys

"Person"

[["born", "name"]]

"Movie"

[["released", "tagline", "title"], ["released", "title"]]

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