比较符¶
NebulaGraph 支持的比较符如下。
符号 | 说明 |
---|---|
= |
赋值 |
+ |
加法 |
- |
减法 |
* |
乘法 |
/ |
除法 |
== |
相等 |
!= , <> |
不等于 |
> |
大于 |
>= |
大于等于 |
< |
小于 |
<= |
小于等于 |
% |
取模 |
- |
负数符号 |
IS NULL |
为 NULL |
IS NOT NULL |
不为 NULL |
IS EMPTY |
不存在 |
IS NOT EMPTY |
存在 |
比较操作的结果是true
或者false
。
Note
- 比较不同类型的值通常没有定义,结果可能是
NULL
或其它。
EMPTY
当前仅用于判断,不支持函数或者运算操作,包括且不限于GROUP BY
、count()
、sum()
、max()
、hash()
、collect()
、+
、*
。
OpenCypher 兼容性¶
openCypher 中没有EMPTY
,因此不支持在 MATCH 语句中使用EMPTY
。
示例¶
==
¶
字符串比较时,会区分大小写。不同类型的值不相等。
Note
nGQL 中的相等符号是==
,openCypher 中的相等符号是=
。
nebula> RETURN 'A' == 'a', toUpper('A') == toUpper('a'), toLower('A') == toLower('a');
+------------+------------------------------+------------------------------+
| ("A"=="a") | (toUpper("A")==toUpper("a")) | (toLower("A")==toLower("a")) |
+------------+------------------------------+------------------------------+
| false | true | true |
+------------+------------------------------+------------------------------+
nebula> RETURN '2' == 2, toInteger('2') == 2;
+----------+---------------------+
| ("2"==2) | (toInteger("2")==2) |
+----------+---------------------+
| false | true |
+----------+---------------------+
>
¶
nebula> RETURN 3 > 2;
+-------+
| (3>2) |
+-------+
| true |
+-------+
nebula> WITH 4 AS one, 3 AS two \
RETURN one > two AS result;
+--------+
| result |
+--------+
| true |
+--------+
>=
¶
nebula> RETURN 2 >= "2", 2 >= 2;
+----------+--------+
| (2>="2") | (2>=2) |
+----------+--------+
| __NULL__ | true |
+----------+--------+
<
¶
nebula> YIELD 2.0 < 1.9;
+---------+
| (2<1.9) |
+---------+
| false |
+---------+
<=
¶
nebula> YIELD 0.11 <= 0.11;
+--------------+
| (0.11<=0.11) |
+--------------+
| true |
+--------------+
!=
¶
nebula> YIELD 1 != '1';
+----------+
| (1!="1") |
+----------+
| true |
+----------+
IS [NOT] NULL
¶
nebula> RETURN null IS NULL AS value1, null == null AS value2, null != null AS value3;
+--------+----------+----------+
| value1 | value2 | value3 |
+--------+----------+----------+
| true | __NULL__ | __NULL__ |
+--------+----------+----------+
nebula> RETURN length(NULL), size(NULL), count(NULL), NULL IS NULL, NULL IS NOT NULL, sin(NULL), NULL + NULL, [1, NULL] IS NULL;
+--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
| length(NULL) | size(NULL) | count(NULL) | NULL IS NULL | NULL IS NOT NULL | sin(NULL) | (NULL+NULL) | [1,NULL] IS NULL |
+--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
| __NULL__ | __NULL__ | 0 | true | false | __NULL__ | __NULL__ | false |
+--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
nebula> WITH {name: null} AS `map` \
RETURN `map`.name IS NOT NULL;
+----------------------+
| map.name IS NOT NULL |
+----------------------+
| false |
+----------------------+
nebula> WITH {name: 'Mats', name2: 'Pontus'} AS map1, \
{name: null} AS map2, {notName: 0, notName2: null } AS map3 \
RETURN map1.name IS NULL, map2.name IS NOT NULL, map3.name IS NULL;
+-------------------+-----------------------+-------------------+
| map1.name IS NULL | map2.name IS NOT NULL | map3.name IS NULL |
+-------------------+-----------------------+-------------------+
| false | false | true |
+-------------------+-----------------------+-------------------+
nebula> MATCH (n:player) \
RETURN n.player.age IS NULL, n.player.name IS NOT NULL, n.player.empty IS NULL;
+----------------------+---------------------------+------------------------+
| n.player.age IS NULL | n.player.name IS NOT NULL | n.player.empty IS NULL |
+----------------------+---------------------------+------------------------+
| false | true | true |
| false | true | true |
...
IS [NOT] EMPTY
¶
nebula> RETURN null IS EMPTY;
+---------------+
| NULL IS EMPTY |
+---------------+
| false |
+---------------+
nebula> RETURN "a" IS NOT EMPTY;
+------------------+
| "a" IS NOT EMPTY |
+------------------+
| true |
+------------------+
nebula> GO FROM "player100" OVER * WHERE properties($$).name IS NOT EMPTY YIELD dst(edge);
+-------------+
| dst(EDGE) |
+-------------+
| "team204" |
| "player101" |
| "player125" |
+-------------+
最后更新:
September 4, 2023