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字符串Graph

NebulaGraph使用关键字string（变长）或fixed_string(<length>)（定长）声明字符串类型数据，格式为双引号或单引号包裹的任意长度的字符串，例如"Shaquille O'Neal"或'This is a single-quoted literal string'。

字符串类型Graph

NebulaGraph支持定长字符串和变长字符串。示例如下：

  • 定长字符串
    nebula> CREATE TAG t1 (p1 fixed_string(10));
  • 变长字符串
    nebula> CREATE TAG t2 (p2 string);

转义字符Graph

字符串中不支持直接换行，可以使用转义字符实现，例如：

  • "\n\t\r\b\f"
  • "\110ello world"

OpenCypher兼容性Graph

openCypher、Cypher和nGQL之间有一些细微区别，例如下面openCypher的示例，不能将单引号替换为双引号。

# File: Literals.feature
Feature: Literals

Background:
    Given any graph
 Scenario: Return a single-quoted string
    When executing query:
      """
      RETURN '' AS literal
      """
    Then the result should be, in any order:
      | literal |
      | ''      |    # Note: it should return single-quotes as openCypher required.
    And no side effects

Cypher的返回结果同时支持单引号和双引号，nGQL遵循Cypher的方式。

nebula > YIELD '' AS quote1, "" AS quote2, "'" AS quote3, '"' AS quote4
+--------+--------+--------+--------+
| quote1 | quote2 | quote3 | quote4 |
+--------+--------+--------+--------+
| ""     | ""     | "'"    | """    |
+--------+--------+--------+--------+
最后更新: 2021年8月19日
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