ORDER BY¶
ORDER BY
子句指定输出结果的排序规则。
- 在原生 nGQL 中,必须在
YIELD
子句之后使用管道符(|)和ORDER BY
子句。
- 在 openCypher 方式中,不允许使用管道符。在
RETURN
子句之后使用ORDER BY
子句。
排序规则分为如下两种:
ASC
(默认): 升序。DESC
: 降序。
原生 nGQL 语法¶
<YIELD clause>
| ORDER BY <expression> [ASC | DESC] [, <expression> [ASC | DESC] ...];
Compatibility
原生 nGQL 语法中,ORDER BY
命令后必须使用引用符$-.
。但在 2.5.0 之前的版本中不需要。
示例¶
nebula> FETCH PROP ON player "player100", "player101", "player102", "player103" \
YIELD properties(vertex).age AS age, properties(vertex).name AS name \
| ORDER BY $-.age ASC, $-.name DESC;
+-----+---------------------+
| age | name |
+-----+---------------------+
| 32 | "Rudy Gay" |
| 33 | "LaMarcus Aldridge" |
| 36 | "Tony Parker" |
| 42 | "Tim Duncan" |
+-----+---------------------+
nebula> $var = GO FROM "player100" OVER follow \
YIELD dst(edge) AS dst; \
ORDER BY $var.dst DESC;
+-------------+
| dst |
+-------------+
| "player125" |
| "player101" |
+-------------+
OpenCypher 方式语法¶
<RETURN clause>
ORDER BY <expression> [ASC | DESC] [, <expression> [ASC | DESC] ...];
示例¶
nebula> MATCH (v:player) RETURN v.player.name AS Name, v.player.age AS Age \
ORDER BY Name DESC;
+-----------------+-----+
| Name | Age |
+-----------------+-----+
| "Yao Ming" | 38 |
| "Vince Carter" | 42 |
| "Tracy McGrady" | 39 |
| "Tony Parker" | 36 |
| "Tim Duncan" | 42 |
+-----------------+-----+
...
# 首先以年龄排序,如果年龄相同,再以姓名排序。
nebula> MATCH (v:player) RETURN v.player.age AS Age, v.player.name AS Name \
ORDER BY Age DESC, Name ASC;
+-----+-------------------+
| Age | Name |
+-----+-------------------+
| 47 | "Shaquille O'Neal" |
| 46 | "Grant Hill" |
| 45 | "Jason Kidd" |
| 45 | "Steve Nash" |
+-----+-------------------+
...
NULL 值的排序¶
升序排列时,会在输出的最后列出 NULL 值,降序排列时,会在输出的开头列出 NULL 值。
nebula> MATCH (v:player{name:"Tim Duncan"}) --> (v2) \
RETURN v2.player.name AS Name, v2.player.age AS Age \
ORDER BY Age;
+-----------------+----------+
| Name | Age |
+-----------------+----------+
| "Tony Parker" | 36 |
| "Manu Ginobili" | 41 |
| __NULL__ | __NULL__ |
+-----------------+----------+
nebula> MATCH (v:player{name:"Tim Duncan"}) --> (v2) \
RETURN v2.player.name AS Name, v2.player.age AS Age \
ORDER BY Age DESC;
+-----------------+----------+
| Name | Age |
+-----------------+----------+
| __NULL__ | __NULL__ |
| "Manu Ginobili" | 41 |
| "Tony Parker" | 36 |
+-----------------+----------+
最后更新:
September 4, 2023