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。
语法¶
ngql
UNWIND <list> AS <alias> <RETURN clause>;
拆分列表¶
ngql
nebula> UNWIND [1,2,3] AS n RETURN n;
+---+
| n |
+---+
| 1 |
| 2 |
| 3 |
+---+
返回去重列表¶
在UNWIND语句中使用WITH DISTINCT可以将列表中的重复项忽略，返回去重后的结果。
示例 1¶
- 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。
ngql
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] |
+------------+
示例 2¶
- 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。
ngql
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"})] |
+----------------------------------------------------------------------------------------------------------------------+