概述

可在MATCH语句的最后使用图模式YIELD从句，选取所需绑定表的列，以便在后续查询展示。

<match statement> ::=
  [ "OPTIONAL" ] "MATCH" <graph pattern> [ <graph pattern yield clause> ]

<graph pattern yield clause> ::=
  "YIELD" <graph pattern yield item> [ { "," <graph pattern yield item> }... ]

<graph pattern yield item> ::= <element variable> | <path variable>

示例图集

以下示例根据该图集运行：

在空图集中运行以下语句创建示例图集：

INSERT (rowlock:User {_id: 'U01', name: 'rowlock'}),
       (brainy:User {_id: 'U02', name: 'Brainy'}),
       (purplechalk:User {_id: 'U03', name: 'purplechalk'}),
       (mochaeach:User {_id: 'U04', name: 'mochaeach'}),
       (lionbower:User {_id: 'U05', name: 'lionbower'}),
       (c01:Club {_id: 'C01', since: 2005}),
       (c02:Club {_id: 'C02', since: 2005}),
       (rowlock)-[:Follows {createdOn: '2024-1-5'}]->(brainy),
       (mochaeach)-[:Follows {createdOn: '2024-2-10'}]->(brainy),
       (brainy)-[:Follows {createdOn: '2024-2-1'}]->(purplechalk),
       (purplechalk)-[:Follows {createdOn: '2024-5-3'}]->(lionbower),
       (brainy)-[:Joins {memberNo: 1}]->(c01),
       (lionbower)-[:Joins {memberNo: 2}]->(c01),
       (mochaeach)-[:Joins {memberNo: 9}]->(c02)

MATCH YIELD

本条查询仅返回与变量n1绑定的数据，因为它是YIELD从句指定的唯一变量：

MATCH (n1:User), (n2:Club)
YIELD n1
RETURN *

结果：n1

本条查询会引发语法错误，因为n2未在YIELD从句中选择，也就无法通过RETURN语句访问：

MATCH (n1:User), (n2:Club)
YIELD n1
RETURN n1, n2

结果：未发现n2

本条查询返回n1和e：

MATCH (n1:Club)
MATCH (n2:Club)<-[e:Joins WHERE e.memberNo < 3]-()
YIELD e
RETURN *

结果：

n1

e