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Create a Collection with Collation使用排序规则创建集合

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Collation allows you to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.排序规则允许您为字符串比较指定特定于语言的规则，例如大小写和重音标记的规则。

Procedure过程

1

Click the Create Collection button.单击“创建集合”按钮。

From the Collections screen, click the Create Collection button.在“集合”屏幕中，单击“创建集合”按钮。

2

Enter the collection name.输入集合名称。

3

Click the Advanced Collection Options dropdown.单击“高级集合选项”下拉列表。

Check the Use Custom Collaton option.选中“使用自定义排序规则”选项。

4

Select a value for locale.选择“区域设置”的值。

You are required to select a locale from the MongoDB supported languages.您需要从MongoDB支持的语言中选择一个“区域设置”。

All other collation options parameters are optional. 所有其他排序规则选项参数都是可选的。For descriptions of the fields, see Collation.有关字段的描述，请参阅排序规则。

5

Click Create Collection to create the collection.单击“创建集合”以创建集合。

Restrictions and Limitations限制和局限性

The following restrictions apply when the parameter numericOrdering is set to true:当参数numericOrdering设置为true时，以下限制适用：

  • Only contiguous non-negative integer substrings of digits are considered in the comparisons. 在比较中只考虑数字的连续非负整数子串。numericOrdering does not support:numericOrdering不支持：

    • +
    • -
    • exponents
  • Only Unicode code points in the Number or Decimal Digit (Nd) category are treated as digits.只有数字或十进制数字（Nd）类别中的Unicode代码点被视为数字。
  • If the number length exceeds 254 characters, the excess characters are treated as a separate number.如果数字长度超过254个字符，则多余的字符将被视为单独的数字。

Example实例

Consider a collection with the following string number and decimal values:考虑具有以下字符串编号和十进制值的集合：

[
{ "n": "1" },
{ "n": "2" },
{ "n": "-2.1" },
{ "n": "2.0" },
{ "n": "2.20" },
{ "n": "10"},
{ "n": "20" },
{ "n": "20.1" },
{ "n": "-10" },
{ "n": "3" }

]

The following find query uses a collation document containing the numericOrdering parameter:以下查找查询使用包含numericOrdering参数的排序规则文档：

db.c.find(
{ }, { _id: 0 }
).sort(
{ n: 1 }
).collation( {
locale: 'en_US',
numericOrdering: true
} )

For more information on querying documents in Compass, see Query Your Data.有关在Compass中查询文档的详细信息，请参阅查询您的数据。

The operations returns the following results:操作返回以下结果：

[
{ "n": "-2.1" },
{ "n": "-10" },
{ "n": "1" },
{ "n": "2" },
{ "n": "2.0" }
{ "n": "2.20" },
{ "n": "3" },
{ "n": "10" },
{ "n": "20" },
{"n": "20.1" }
]
  • numericOrdering: true sorts the string values in ascending order as if they were numeric values.numericOrdering: true按升序对字符串值进行排序，就好像它们是数值一样。
  • The two negative values -2.1 and -10 are not sorted in the expected sort order because they have unsupported - characters.两个负值-2.1和-10没有按预期的排序顺序排序，因为它们包含不支持的-字符。