谓词函数

    Nebula Graph支持以下谓词函数。

    如果列表为空，或者列表中的所有元素都为空，则返回NULL。

    在 openCypher 中只定义了函数exists()，其他几个函数依赖于具体实现。

    示例

    1. nebula> RETURN any(n IN [1, 2, 3, 4, 5, NULL] \
    2.         WHERE n > 2) AS r;
    3. +------+
    4. | r    |
    5. +------+
    6. | true |
    7. +------+
    9. nebula> RETURN single(n IN range(1, 5) \
    10.         WHERE n == 3) AS r;
    11. +------+
    12. | r    |
    13. +------+
    14. | true |
    15. +------+
    17. nebula> RETURN none(n IN range(1, 3) \
    18.         WHERE n == 0) AS r;
    19. +------+
    20. | r    |
    21. +------+
    22. | true |
    24. nebula> WITH [1, 2, 3, 4, 5, NULL] AS a \
    25.         RETURN any(n IN a WHERE n > 2);
    26. +-------------------------+
    27. | any(n IN a WHERE (n>2)) |
    28. +-------------------------+
    29. | true                    |
    30. +-------------------------+
    32. nebula> MATCH p = (n:player{name:"LeBron James"})<-[:follow]-(m) \
    33.         RETURN nodes(p)[0].name AS n1, nodes(p)[1].name AS n2, \
    34.         all(n IN nodes(p) WHERE n.name NOT STARTS WITH "D") AS b;
    35. +----------------+-------------------+-------+
    36. | n1             | n2                | b     |
    37. +----------------+-------------------+-------+
    38. | "LeBron James" | "Danny Green"     | false |
    39. | "LeBron James" | "Dejounte Murray" | false |
    40. | "LeBron James" | "Chris Paul"      | true  |
    41. | "LeBron James" | "Kyrie Irving"    | true  |
    42. | "LeBron James" | "Carmelo Anthony" | true  |
    43. | "LeBron James" | "Dwyane Wade"     | false |
    46. nebula> MATCH p = (n:player{name:"LeBron James"})-[:follow]->(m) \
    47. +------+
    48. | b    |
    49. +------+
    50. | true |
    51. +------+
    53. nebula> MATCH (n:player) \
    54.         RETURN exists(n.id), n IS NOT NULL;
    55. +--------------+---------------+
    56. | exists(n.id) | n IS NOT NULL |
    57. +--------------+---------------+
    58. | false        | true          |
    59. +--------------+---------------+
    60. ...
    62. nebula> MATCH (n:player) \
    63.         WHERE exists(n['name']) \
    64.         RETURN n;
    65. +---------------------------------------------------------------+
    66. | n                                                             |
    67. +---------------------------------------------------------------+
    68. | ("player105" :player{age: 31, name: "Danny Green"})           |
    69. | ("player109" :player{age: 34, name: "Tiago Splitter"})        |
    70. | ("player111" :player{age: 38, name: "David West"})            |