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$not

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Definition定义

$not

Syntax: { field: { $not: { <operator-expression> } } }

$not performs a logical NOT operation on the specified <operator-expression> and selects the documents that do not match the <operator-expression>. 对指定的<operator-expression>执行逻辑NOT运算，并选择与<operator-expression>不匹配的文档。This includes documents that do not contain the field.这包括不包含该field的文档。

Consider the following query:请考虑以下查询：

db.inventory.find( { price: { $not: { $gt: 1.99 } } } )

This query will select all documents in the inventory collection where:此查询将选择inventory集合中的所有文档，其中：

  • the price field value is less than or equal to 1.99 orprice字段值小于或等于1.99，或者
  • the price field does not existprice字段不存在

{ $not: { $gt: 1.99 } } is different from the $lte operator. 与$lte运算符不同。{ $lte: 1.99 } returns only the documents where price field exists and its value is less than or equal to 1.99.仅返回存在price字段且其值小于或等于1.99的文档。

Remember that the $not operator only affects other operators and cannot check fields and documents independently. 请记住，$not运算符只影响其他运算符，不能独立检查字段和文档。So, use the $not operator for logical disjunctions and the $ne operator to test the contents of fields directly.因此，使用$not运算符进行逻辑析取，使用$ne运算符直接测试字段的内容。

Behavior行为

$not and Data Types和数据类型

The operation of the $not operator is consistent with the behavior of other operators but may yield unexpected results with some data types like arrays.$not运算符的操作与其他运算符的行为一致，但对于某些数据类型（如数组）可能会产生意外结果。

$not and Regular Expressions和正则表达式

$not operator can perform logical NOT operation on:运算符可以对以下项执行逻辑NOT操作：

  • Regular expression objects (i.e. /pattern/)正则表达式对象（即/pattern/）

    For example, the following query selects all documents in the inventory collection where the item field value does not start with the letter p.例如，以下查询选择inventory集合中item字段值不以字母p开头的所有文档。

    db.inventory.find( { item: { $not: /^p.*/ } } )
  • $regex operator expression运算符表达式

    For example, the following query selects all documents in the inventory collection where the item field value does not start with the letter p.例如，以下查询选择inventory集合中物料字段值不以字母p开头的所有文档。

    db.inventory.find( { item: { $not: { $regex: "^p.*" } } } )
    db.inventory.find( { item: { $not: { $regex: /^p.*/ } } } )
  • driver language's regular expression objects驱动程序语言的正则表达式对象

    For example, the following PyMongo query uses Python's re.compile() method to compile a regular expression:例如，以下PyMongo查询使用Python的re.compile()方法编译正则表达式：

    import re
    for noMatch in db.inventory.find( { "item": { "$not": re.compile("^p.*") } } ):
        print noMatch
Tip

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