$not

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Definition

Compatibility
Syntax
Behavior

Definition

$not: $not performs a logical NOT operation on the specified <operator-expression> and selects the documents that do not match the <operator-expression>. This includes documents that do not contain the field.

Compatibility

You can use $not for deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The $not operator has the following form:

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

Consider the following example:

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

This query will select all documents in the inventory collection where:

the price field value is less than or equal to 1.99 or
the price field does not exist

{ $not: { $gt: 1.99 } } is different from the $lte operator. { $lte: 1.99 } returns only the documents where price field exists and its value is less than or equal to 1.99.

You must use the $not operator with another operator expression. For example, to use $not to perform an inequality check, use this syntax:

{ price: { $not: { $eq: 1.99 } } }

The preceding query is equivalent to:

{ price: { $ne: 1.99 } }

The following $not query is invalid because it attempts to compare a field without an operator:

{ price: { $not: 1.99 } }

Behavior

Arrays

When passed an array argument, the $not operator may yield unexpected results. To match documents based on multiple false conditions, use $nor.

Regular Expressions

$not operator can perform logical NOT operation on:

Regular expression objects (i.e. /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.
```
db.inventory.find( { item: { $not: /^p.*/ } } )
```
$regex operator expression
For example, the following query selects all documents in the inventory collection where the item field value does not start with the letter p.
```
db.inventory.find( { item: { $not: { $regex: "^p.*" } } } )
db.inventory.find( { item: { $not: { $regex: /^p.*/ } } } )
```
driver language's regular expression objects
For example, the following PyMongo query uses Python's re.compile() method to compile a regular expression:
```
import re
for noMatch in db.inventory.find( { "item": { "$not": re.compile("^p.*") } } ):
    print noMatch
```