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RETURN

RETURN子句定义了 nGQL 查询的输出结果。如果需要返回多个字段，用英文逗号（,）分隔。

RETURN可以引导子句或语句：

  • RETURN子句可以用于 nGQL 中的 openCypher 方式语句中，例如MATCH或UNWIND。
  • RETURN可以单独使用，输出表达式的结果。

openCypher 兼容性

本文操作仅适用于 nGQL 中的 openCypher 方式。关于原生 nGQL 如何定义输出结果，请参见 YIELD。

RETURN不支持如下 openCypher 功能：

  • 使用不在英文字母表中的字符作为变量名。例如：

    ngql MATCH (`点 1`:player) \ RETURN `点 1`;

  • 设置一个模式，并返回该模式匹配的所有元素。例如：

    ngql MATCH (v:player) \ RETURN (v)-[e]->(v2);

历史版本兼容性

  • 在 nGQL 1.x 中，RETURN适用于原生 nGQL，语法为RETURN <var_ref> IF <var_ref> IS NOT NULL。
  • 从 nGQL 2.0 开始，RETURN不适用于原生 nGQL。

Map 顺序说明

RETURN返回 Map 时，Key 的顺序是未定义的。

```ngql nebula> RETURN {age: 32, name: "Marco Belinelli"}; +------------------------------------+ | {age:32,name:"Marco Belinelli"} | +------------------------------------+ | {age: 32, name: "Marco Belinelli"} | +------------------------------------+

nebula> RETURN {zage: 32, name: "Marco Belinelli"}; +-------------------------------------+ | {zage:32,name:"Marco Belinelli"} | +-------------------------------------+ | {name: "Marco Belinelli", zage: 32} | +-------------------------------------+ ```

返回点或边

使用RETURN {<vertex_name> | <edge_name>}返回点或边的所有信息。

```ngql // 返回点 nebula> MATCH (v:player) \ RETURN v; +---------------------------------------------------------------+ | v | +---------------------------------------------------------------+ | ("player104" :player{age: 32, name: "Marco Belinelli"}) | | ("player107" :player{age: 32, name: "Aron Baynes"}) | | ("player116" :player{age: 34, name: "LeBron James"}) | | ("player120" :player{age: 29, name: "James Harden"}) | | ("player125" :player{age: 41, name: "Manu Ginobili"}) | +---------------------------------------------------------------+ ...

// 返回边 nebula> MATCH (v:player)-[e]->() \ RETURN e; +------------------------------------------------------------------------------+ | e | +------------------------------------------------------------------------------+ | [:follow "player104"->"player100" @0 {degree: 55}] | | [:follow "player104"->"player101" @0 {degree: 50}] | | [:follow "player104"->"player105" @0 {degree: 60}] | | [:serve "player104"->"team200" @0 {end_year: 2009, start_year: 2007}] | | [:serve "player104"->"team208" @0 {end_year: 2016, start_year: 2015}] | +------------------------------------------------------------------------------+ ... ```

返回点 ID

使用id()函数返回点 ID。 ngql nebula> MATCH (v:player{name:"Tim Duncan"}) \ RETURN id(v); +-------------+ | id(v) | +-------------+ | "player100" | +-------------+

返回 Tag

使用labels()函数返回点上的 Tag 列表。

ngql nebula> MATCH (v:player{name:"Tim Duncan"}) \ RETURN labels(v); +------------+ | labels(v) | +------------+ | ["player"] | +------------+

返回列表labels(v)中的第 N 个元素，可以使用labels(v)[n-1]。例如下面示例使用labels(v)[0]检索第一个元素。

ngql nebula> MATCH (v:player{name:"Tim Duncan"}) \ RETURN labels(v)[0]; +--------------+ | labels(v)[0] | +--------------+ | "player" | +--------------+

返回属性

使用语法{<vertex_name>|<edge_name>}.<property>返回点或边的属性。

ngql nebula> MATCH (v:player) \ RETURN v.player.name, v.player.age \ LIMIT 3; +------------------+--------------+ | v.player.name | v.player.age | +------------------+--------------+ | "Danny Green" | 31 | | "Tiago Splitter" | 34 | | "David West" | 38 | +------------------+--------------+

使用properties()函数返回点或边的所有属性。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) \ RETURN properties(v2); +----------------------------------+ | properties(v2) | +----------------------------------+ | {name: "Spurs"} | | {age: 36, name: "Tony Parker"} | | {age: 41, name: "Manu Ginobili"} | +----------------------------------+

返回 Edge type

使用type()函数返回匹配的 Edge type。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[e]->() \ RETURN DISTINCT type(e); +----------+ | type(e) | +----------+ | "serve" | | "follow" | +----------+

返回路径

使用RETURN <path_name>返回匹配路径的所有信息。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[*3]->() \ RETURN p; +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | p | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 90}]->("player102" :player{age: 33, name: "LaMarcus Aldridge"})-[:serve@0 {end_year: 2019, start_year: 2015}]->("team204" :team{name: "Spurs"})> | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 90}]->("player102" :player{age: 33, name: "LaMarcus Aldridge"})-[:serve@0 {end_year: 2015, start_year: 2006}]->("team203" :team{name: "Trail Blazers"})> | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 90}]->("player102" :player{age: 33, name: "LaMarcus Aldridge"})-[:follow@0 {degree: 75}]->("player101" :player{age: 36, name: "Tony Parker"})> | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ ...

返回路径中的点

使用nodes()函数返回路径中的所有点。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) \ RETURN nodes(p); +---------------------------------------------------------------------------------------------------------------------+ | nodes(p) | +---------------------------------------------------------------------------------------------------------------------+ | [("player100" :star{} :player{age: 42, name: "Tim Duncan"}), ("player204" :team{name: "Spurs"})] | | [("player100" :star{} :player{age: 42, name: "Tim Duncan"}), ("player101" :player{name: "Tony Parker", age: 36})] | | [("player100" :star{} :player{age: 42, name: "Tim Duncan"}), ("player125" :player{name: "Manu Ginobili", age: 41})] | +---------------------------------------------------------------------------------------------------------------------+

返回路径中的边

使用relationships()函数返回路径中的所有边。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[]->(v2) \ RETURN relationships(p); +-------------------------------------------------------------------------+ | relationships(p) | +-------------------------------------------------------------------------+ | [[:serve "player100"->"team204" @0 {end_year: 2016, start_year: 1997}]] | | [[:follow "player100"->"player101" @0 {degree: 95}]] | | [[:follow "player100"->"player125" @0 {degree: 95}]] | +-------------------------------------------------------------------------+

返回路径长度

使用length()函数检索路径的长度。

ngql nebula> MATCH p=(v:player{name:"Tim Duncan"})-[*..2]->(v2) \ RETURN p AS Paths, length(p) AS Length; +------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+ | Paths | Length | +------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+ | <("player100" :player{age: 42, name: "Tim Duncan"})-[:serve@0 {end_year: 2016, start_year: 1997}]->("team204" :team{name: "Spurs"})> | 1 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})> | 1 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player125" :player{age: 41, name: "Manu Ginobili"})> | 1 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:serve@0 {end_year: 2018, start_year: 1999}]->("team204" :team{name: "Spurs"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:serve@0 {end_year: 2019, start_year: 2018}]->("team215" :team{name: "Hornets"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 95}]->("player100" :player{age: 42, name: "Tim Duncan"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 90}]->("player102" :player{age: 33, name: "LaMarcus Aldridge"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player101" :player{age: 36, name: "Tony Parker"})-[:follow@0 {degree: 95}]->("player125" :player{age: 41, name: "Manu Ginobili"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player125" :player{age: 41, name: "Manu Ginobili"})-[:serve@0 {end_year: 2018, start_year: 2002}]->("team204" :team{name: "Spurs"})> | 2 | | <("player100" :player{age: 42, name: "Tim Duncan"})-[:follow@0 {degree: 95}]->("player125" :player{age: 41, name: "Manu Ginobili"})-[:follow@0 {degree: 90}]->("player100" :player{age: 42, name: "Tim Duncan"})> | 2 | +------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+--------+

返回所有元素

使用星号（*）返回匹配模式中的所有元素。

```ngql nebula> MATCH (v:player{name:"Tim Duncan"}) \ RETURN *; +----------------------------------------------------+ | v | +----------------------------------------------------+ | ("player100" :player{age: 42, name: "Tim Duncan"}) | +----------------------------------------------------+

nebula> MATCH (v:player{name:"Tim Duncan"})-[e]->(v2) \ RETURN *; +----------------------------------------------------+-----------------------------------------------------------------------+-------------------------------------------------------+ | v | e | v2 | +----------------------------------------------------+-----------------------------------------------------------------------+-------------------------------------------------------+ | ("player100" :player{age: 42, name: "Tim Duncan"}) | [:follow "player100"->"player101" @0 {degree: 95}] | ("player101" :player{age: 36, name: "Tony Parker"}) | | ("player100" :player{age: 42, name: "Tim Duncan"}) | [:follow "player100"->"player125" @0 {degree: 95}] | ("player125" :player{age: 41, name: "Manu Ginobili"}) | | ("player100" :player{age: 42, name: "Tim Duncan"}) | [:serve "player100"->"team204" @0 {end_year: 2016, start_year: 1997}] | ("team204" :team{name: "Spurs"}) | +----------------------------------------------------+-----------------------------------------------------------------------+-------------------------------------------------------+ ```

重命名字段

使用语法AS <alias>重命名输出结果中的字段。

```ngql nebula> MATCH (v:player{name:"Tim Duncan"})-[:serve]->(v2) \ RETURN v2.team.name AS Team; +---------+ | Team | +---------+ | "Spurs" | +---------+

nebula> RETURN "Amber" AS Name; +---------+ | Name | +---------+ | "Amber" | +---------+ ```

返回不存在的属性

如果匹配的结果中，某个属性不存在，会返回NULL。

ngql nebula> MATCH (v:player{name:"Tim Duncan"})-[e]->(v2) \ RETURN v2.player.name, type(e), v2.player.age; +-----------------+----------+---------------+ | v2.player.name | type(e) | v2.player.age | +-----------------+----------+---------------+ | "Manu Ginobili" | "follow" | 41 | | __NULL__ | "serve" | __NULL__ | | "Tony Parker" | "follow" | 36 | +-----------------+----------+---------------+

返回表达式结果

RETURN语句可以返回字面量、函数或谓词等表达式的结果。

```ngql nebula> MATCH (v:player{name:"Tony Parker"})-->(v2:player) \ RETURN DISTINCT v2.player.name, "Hello"+" graphs!", v2.player.age > 35; +---------------------+----------------------+--------------------+ | v2.player.name | ("Hello"+" graphs!") | (v2.player.age>35) | +---------------------+----------------------+--------------------+ | "LaMarcus Aldridge" | "Hello graphs!" | false | | "Tim Duncan" | "Hello graphs!" | true | | "Manu Ginobili" | "Hello graphs!" | true | +---------------------+----------------------+--------------------+

nebula> RETURN 1+1; +-------+ | (1+1) | +-------+ | 2 | +-------+

nebula> RETURN 3 > 1; +-------+ | (3>1) | +-------+ | true | +-------+

nebula> RETURN 1+1, rand32(1, 5); +-------+-------------+ | (1+1) | rand32(1,5) | +-------+-------------+ | 2 | 1 | +-------+-------------+ ```

返回唯一字段

使用DISTINCT可以删除结果集中的重复字段。

```ngql

未使用 DISTINCT。

nebula> MATCH (v:player{name:"Tony Parker"})--(v2:player) \ RETURN v2.player.name, v2.player.age; +---------------------+--------+ | v2.name | v2.age | +---------------------+--------+ | "Tim Duncan" | 42 | | "LaMarcus Aldridge" | 33 | | "Marco Belinelli" | 32 | | "Boris Diaw" | 36 | | "Dejounte Murray" | 29 | | "Tim Duncan" | 42 | | "LaMarcus Aldridge" | 33 | | "Manu Ginobili" | 41 | +---------------------+--------+

使用 DISTINCT。

nebula> MATCH (v:player{name:"Tony Parker"})--(v2:player) \ RETURN DISTINCT v2.player.name, v2.player.age; +---------------------+--------+ | v2.name | v2.age | +---------------------+--------+ | "Tim Duncan" | 42 | | "LaMarcus Aldridge" | 33 | | "Marco Belinelli" | 32 | | "Boris Diaw" | 36 | | "Dejounte Murray" | 29 | | "Manu Ginobili" | 41 | +---------------------+--------+ ```

最后更新: 2026年8月17日