字符串

Nebula Graph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 double-quoted literal string'。

字符串类型

Nebula Graph支持定长字符串和变长字符串。示例如下：

  • 定长字符串

    1. nebula> CREATE TAG t1 (p1 fixed_string(10));

  • 变长字符串

    1. nebula> CREATE TAG t2 (p2 string);

转义字符

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

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。

```ngql # 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

  1. Cypher的返回结果同时支持单引号和双引号，nGQL遵循Cypher的方式。
  3. ```ngql
  4. nebula > YIELD '' AS quote1, "" AS quote2, "'" AS quote3, '"' AS quote4
  5. +--------+--------+--------+--------+
  6. | quote1 | quote2 | quote3 | quote4 |
  7. +--------+--------+--------+--------+
  8. | ""     | ""     | "'"    | """    |
  9. +--------+--------+--------+--------+