比较符Graph
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 |
< |
小于 |
<= |
小于等于 |
% |
取模 |
- |
负数符号 |
IS NULL |
为NULL |
IS NOT NULL |
不为NULL |
比较操作的结果是true或者false。
说明：比较不同类型的值通常没有定义，结果可能是NULL或其它。
OpenCypher兼容性Graph
NebulaGraph中，NULL的比较操作和openCypher不同，行为也可能会改变。在openCypher中，IS [NOT] NULL通常与OPTIONAL MATCH一起使用，但是nGQL不支持OPTIONAL MATCH。
示例Graph
==Graph
字符串比较时，会区分大小写。不同类型的值不相等。
说明：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 |
+----------+---------------------+
>Graph
nebula> RETURN 3 > 2;
+-------+
| (3>2) |
+-------+
| true |
+-------+
nebula> WITH 4 AS one, 3 AS two \
RETURN one > two AS result;
+--------+
| result |
+--------+
| true |
+--------+
>=Graph
nebula> RETURN 2 >= "2", 2 >= 2;
+----------+--------+
| (2>="2") | (2>=2) |
+----------+--------+
| __NULL__ | true |
+----------+--------+
<Graph
nebula> YIELD 2.0 < 1.9;
+---------+
| (2<1.9) |
+---------+
| false |
+---------+
<=Graph
nebula> YIELD 0.11 <= 0.11;
+--------------+
| (0.11<=0.11) |
+--------------+
| true |
+--------------+
!=Graph
nebula> YIELD 1 != '1';
+--------+
| (1!=1) |
+--------+
| true |
+--------+
IS [NOT] NULLGraph
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 |
+--------------+------------+-------------+--------------+------------------+-----------+-------------+------------------+
| BAD_TYPE | __NULL__ | 0 | true | false | BAD_TYPE | __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.age IS NULL, n.name IS NOT NULL, n.empty IS NULL;
+---------------+--------------------+-----------------+
| n.age IS NULL | n.name IS NOT NULL | n.empty IS NULL |
+---------------+--------------------+-----------------+
| false | true | true |
+---------------+--------------------+-----------------+
| false | true | true |
+---------------+--------------------+-----------------+
| false | true | true |
+---------------+--------------------+-----------------+
...
最后更新: March 24, 2021