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列表函数

Nebula Graph支持以下列表(List)函数。

函数 说明
keys(expr) 返回一个列表,包含字符串形式的点、边或映射的所有属性。
labels(vertex) 返回点的Tag列表。
nodes(path) 返回路径中所有点的列表。
range(start, end [, step]) 返回[start,end]范围内固定步长的列表,默认步长step为1。
relationships(path) 返回路径中所有关系的列表。
reverse(list) 返回将原列表逆序排列的新列表。
tail(list) 返回不包含原列表第一个元素的新列表.
head(list) 返回列表的第一个元素。
last(list) 返回列表的最后一个元素。
coalesce(list) 返回列表中第一个非空元素。
reduce() 请参见reduce函数

Note

如果参数为NULL,则输出结果是未定义的。

示例

nebula> WITH [NULL, 4923, 'abc', 521, 487] AS ids \
        RETURN reverse(ids), tail(ids), head(ids), last(ids), coalesce(ids);
+-----------------------------------+-------------------------+-----------+-----------+---------------+
| reverse(ids)                      | tail(ids)               | head(ids) | last(ids) | coalesce(ids) |
+-----------------------------------+-------------------------+-----------+-----------+---------------+
| [487, 521, "abc", 4923, __NULL__] | [4923, "abc", 521, 487] | __NULL__  | 487       | 4923          |
+-----------------------------------+-------------------------+-----------+-----------+---------------+

nebula> MATCH (a:player)-[r]->() \
        WHERE id(a) == "player100" \
        RETURN labels(a),  keys(r);
+------------+----------------------------+
| labels(a)  | keys(r)                    |
+------------+----------------------------+
| ["player"] | ["degree"]                 |
+------------+----------------------------+
| ["player"] | ["degree"]                 |
+------------+----------------------------+
| ["player"] | ["end_year", "start_year"] |
+------------+----------------------------+

nebula> MATCH p = (a:player)-[]->(b)-[]->(c:team) \
        WHERE a.name == "Tim Duncan" AND c.name == "Spurs" \
        RETURN nodes(p);
+-----------------------------------------------------------------------------------------------------------------------------------------------+
| nodes(p)                                                                                                                                      |
+-----------------------------------------------------------------------------------------------------------------------------------------------+
| [("player100" :player{age: 42, name: "Tim Duncan"}), ("player101" :player{age: 36, name: "Tony Parker"}), ("team204" :team{name: "Spurs"})]   |
+-----------------------------------------------------------------------------------------------------------------------------------------------+
| [("player100" :player{age: 42, name: "Tim Duncan"}), ("player125" :player{age: 41, name: "Manu Ginobili"}), ("team204" :team{name: "Spurs"})] |
+-----------------------------------------------------------------------------------------------------------------------------------------------+

nebula> MATCH p = (a:player)-[]->(b)-[]->(c:team) WHERE a.name == "Tim Duncan" AND c.name == "Spurs" RETURN relationships(p);
+-----------------------------------------------------------------------------------------------------------------------------+
| relationships(p)                                                                                                            |
+-----------------------------------------------------------------------------------------------------------------------------+
| [[:follow "player100"->"player101" @0 {degree: 95}], [:serve "player101"->"team204" @0 {end_year: 2018, start_year: 1999}]] |
+-----------------------------------------------------------------------------------------------------------------------------+
| [[:follow "player100"->"player125" @0 {degree: 95}], [:serve "player125"->"team204" @0 {end_year: 2018, start_year: 2002}]] |
+-----------------------------------------------------------------------------------------------------------------------------+

最后更新: August 19, 2021
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