How to Use $nor Operator in MongoDB Queries

In MongoDB, the $nor operator is used to select documents that fail all the given conditions inside an array. It works like a logical NOR, returning documents where none of the specified criteria are true.

Syntax

The $nor operator takes an array of query expressions and returns documents that do not match any of these expressions.

Each element inside the array is a condition that MongoDB tests against the documents.

json

{
  $nor: [
    { <field1>: <condition1> },
    { <field2>: <condition2> },
    ...
  ]
}

Example

This example shows how to find documents in a collection where the status is neither "A" nor "D".

mongodb

db.orders.find({
  $nor: [
    { status: "A" },
    { status: "D" }
  ]
})

Output

[
  { "_id": 3, "item": "notebook", "status": "P" },
  { "_id": 4, "item": "pen", "status": "C" }
]

Common Pitfalls

• Using $nor with an empty array returns all documents because no conditions are negated.
• Confusing $nor with $not: $nor works with multiple conditions, while $not negates a single condition.
• Not wrapping each condition inside its own object in the array causes syntax errors.

mongodb

/* Wrong usage: conditions not wrapped in objects */
db.orders.find({
  $nor: [
    { status: "A" },
    { status: "D" }
  ]
})

/* Correct usage: each condition is an object */
db.orders.find({
  $nor: [
    { status: "A" },
    { status: "D" }
  ]
})

Quick Reference

Operator	Description	Example
$nor	Selects documents that fail all given conditions	{ $nor: [ { age: { $lt: 18 } }, { status: "inactive" } ] }
$not	Negates a single condition	{ age: { $not: { $gt: 30 } } }

Key Takeaways

Use $nor to find documents that do not match any of the specified conditions.

Each condition inside $nor must be an object wrapped in an array.

$nor is different from $not; it works with multiple conditions.

An empty $nor array matches all documents because no conditions are negated.

Test queries carefully to avoid syntax errors with $nor usage.