`Exists`

Cypher® EXISTS 子查询可以使用 new Cypher.Exists() 创建。为此，需要将有效查询传递给 Exists。

请注意，计数子查询也可以在 WHERE 子句中用作谓词，例如

const subquery = new Cypher.Match(new Cypher.Node({ labels: ["Movie"] })).return("*");

const existsExpr = new Cypher.Exists(subquery);
const match = new Cypher.Match(new Cypher.Node()).where(existsExpr).return("*");

MATCH (this0)
WHERE EXISTS {
    MATCH (this1:Movie)
    RETURN *
}
RETURN *

简单的 `Exists` 子查询

可以直接向 Exists 子查询传递 Pattern，而不是 Clause

const existsExpr = new Cypher.Exists(new Cypher.Pattern(new Cypher.Node(), { labels: ["Movie"] }))

const match = new Cypher.Match(new Cypher.Node()).where(existsExpr).return("*");

MATCH (this0)
WHERE EXISTS {
    (this1:Movie)
}
RETURN *

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