UNWIND¶

UNWIND语句可以将列表拆分为单独的行，列表中的每个元素为一行。

UNWIND可以作为单独语句或语句中的子句使用。

UNWIND 语句¶

语法¶

UNWIND <list> AS <alias> <RETURN clause>;

示例¶

拆分列表。

nebula> UNWIND [1,2,3] AS n RETURN n;
+---+
| n |
+---+
| 1 |
| 2 |
| 3 |
+---+

UNWIND 子句¶

语法¶

原生 nGQL 语句中使用UNWIND子句。

Note

在原生 nGQL 语句中使用UNWIND子句时，需要用在管道符|之后，并使用$-引用管道符之前的变量。如果UNWIND后使用语句或子句，需要使用管道符|并且使用$-引用管道符之前的变量。
```
<statement> | UNWIND $-.<var> AS <alias> <|> <clause>;
```

openCypher 语句中使用UNWIND子句。

<statement> UNWIND <list> AS <alias> <RETURN clause>；

示例¶

在UNWIND子句中使用WITH DISTINCT可以将列表中的重复项忽略，返回去重后的结果。

Note

原生 nGQL 语句不支持WITH DISTINCT。

// 拆分列表`[1,1,2,2,3,3]`，删除重复行，排序行，将行转换为列表。
nebula> WITH [1,1,2,2,3,3] AS n \
        UNWIND n AS r \
        WITH DISTINCT r AS r \
        ORDER BY r \
        RETURN collect(r);
+------------+
| collect(r) |
+------------+
| [1, 2, 3]  |
+------------+

MATCH语句中使用UNWIND。

// 将匹配路径上的顶点输出到列表中，拆分列表，删除重复行，将行转换为列表。
nebula> MATCH p=(v:player{name:"Tim Duncan"})--(v2) \
        WITH nodes(p) AS n \
        UNWIND n AS r \
        WITH DISTINCT r AS r \
        RETURN collect(r);
+----------------------------------------------------------------------------------------------------------------------+
| collect(r)                                                                                                           |
+----------------------------------------------------------------------------------------------------------------------+
| [("player100" :player{age: 42, name: "Tim Duncan"}), ("player101" :player{age: 36, name: "Tony Parker"}),            |
|("team204" :team{name: "Spurs"}), ("player102" :player{age: 33, name: "LaMarcus Aldridge"}),                          |
|("player125" :player{age: 41, name: "Manu Ginobili"}), ("player104" :player{age: 32, name: "Marco Belinelli"}),       |
|("player144" :player{age: 47, name: "Shaquile O'Neal"}), ("player105" :player{age: 31, name: "Danny Green"}),         |
|("player113" :player{age: 29, name: "Dejounte Murray"}), ("player107" :player{age: 32, name: "Aron Baynes"}),         |
|("player109" :player{age: 34, name: "Tiago Splitter"}), ("player108" :player{age: 36, name: "Boris Diaw"})]           |  
+----------------------------------------------------------------------------------------------------------------------+

GO语句中使用UNWIND。

// 在点列表中查询点关联的边。
nebula> YIELD ['player101', 'player100'] AS a | UNWIND $-.a AS  b | GO FROM $-.b OVER follow YIELD edge AS e;
+----------------------------------------------------+
| e                                                  |
+----------------------------------------------------+
| [:follow "player101"->"player100" @0 {degree: 95}] |
| [:follow "player101"->"player102" @0 {degree: 90}] |
| [:follow "player101"->"player125" @0 {degree: 95}] |
| [:follow "player100"->"player101" @0 {degree: 95}] |
| [:follow "player100"->"player125" @0 {degree: 95}] |
+----------------------------------------------------+

LOOKUP语句中使用UNWIND。

// 查询年龄大于 46 岁球员的所有属性，去掉重复属性，并将结果转换为行。
nebula> LOOKUP ON player \
        WHERE player.age > 46 \
        YIELD DISTINCT keys(vertex) as p | UNWIND $-.p as a | YIELD $-.a AS a;
+--------+
| a      |
+--------+
| "age"  |
| "name" |
+--------+

FETCH语句中使用UNWIND。

// 查询 player101 点的所有 Tag，并将结果转换为行。
nebula> CREATE TAG hero(like string, height int);
        INSERT VERTEX hero(like, height) VALUES "player101":("deep", 182);
        FETCH PROP ON * "player101" \
        YIELD tags(vertex) as t | UNWIND $-.t as a | YIELD $-.a AS a;
+----------+
| a        |
+----------+
| "hero"   |
| "player" |
+----------+

GET SUBGRAPH语句中使用UNWIND。

// 查询从点 player100 开始、0~2 跳、serve 类型的出边和入边的子图，并将结果转换为行。
nebula> GET SUBGRAPH 2 STEPS FROM "player100" BOTH serve \
        YIELD edges as e | UNWIND $-.e as a | YIELD $-.a AS a;
+----------------------------------------------+
| a                                            |
+----------------------------------------------+
| [:serve "player100"->"team204" @0 {}]        |
| [:serve "player101"->"team204" @0 {}]        |
| [:serve "player102"->"team204" @0 {}]        |
| [:serve "player103"->"team204" @0 {}]        |
| [:serve "player105"->"team204" @0 {}]        |
| [:serve "player106"->"team204" @0 {}]        |
| [:serve "player107"->"team204" @0 {}]        |
| [:serve "player108"->"team204" @0 {}]        |
| [:serve "player109"->"team204" @0 {}]        |
| [:serve "player110"->"team204" @0 {}]        |
| [:serve "player111"->"team204" @0 {}]        |
| [:serve "player112"->"team204" @0 {}]        |
| [:serve "player113"->"team204" @0 {}]        |
| [:serve "player114"->"team204" @0 {}]        |
| [:serve "player125"->"team204" @0 {}]        |
| [:serve "player138"->"team204" @0 {}]        |
| [:serve "player104"->"team204" @20132015 {}] |
| [:serve "player104"->"team204" @20182019 {}] |
+----------------------------------------------+

FIND PATH语句中使用UNWIND。

// 找出 player101 到 team204 延 serve 类型边的最短路径上的所有点，并将结果转换为行。
nebula> FIND SHORTEST PATH FROM "player101" TO "team204" OVER serve \
        YIELD path as p | YIELD nodes($-.p) AS nodes | UNWIND $-.nodes AS a | YIELD $-.a AS a;
+---------------+
| a             |
+---------------+
| ("player101") |
| ("team204")   |
+---------------+

最后更新: 2024年12月19日