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$nin

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$nin

Syntax: { field: { $nin: [ <value1>, <value2> ... <valueN> ] } }

$nin selects the documents where:

  • the field value is not in the specified array or

  • the field does not exist.

If the field holds an array, then the $nin operator selects the documents whose field holds an array with no element equal to a value in the specified array (for example, <value1>, <value2>, and so on).

For comparison of different BSON type values, see the specified BSON comparison order.

Examples

Create the inventory collection:

db.inventory.insertMany( [
   { "item": "Pens", "quantity": 350, "tags": [ "school", "office" ] },
   { "item": "Erasers", "quantity": 15, "tags": [ "school", "home" ] },
   { "item": "Maps", "tags": [ "office", "storage" ] },
   { "item": "Books", "quantity": 5, "tags": [ "school", "storage", "home" ] }
] )

Select on Unmatching Documents

The following query selects all documents from the inventory collection where the quantity does not equal either 5 or 15.

The query also matches documents that do not have a quantity field.

db.inventory.find( { quantity: { $nin: [ 5, 15 ] } }, { _id: 0 } )

Example output:

{ item: 'Pens', quantity: 350, tags: [ 'school', 'office' ] },
{ item: 'Maps', tags: [ 'office', 'storage' ] }

Select on Elements Not in an Array

Set the exclude field to true for documents that don't have the "school" tag.

db.inventory.updateMany(
    { tags: { $nin: [ "school" ] } },
    { $set: { exclude: true } }
)

updateMany() also selects a document when the document does not contain the field $nin is matching on.

The inequality operator $nin is not very selective since it often matches a large portion of the index. As a result, in many cases, a $nin query with an index may perform no better than a $nin query that must scan all documents in a collection. See also Query Selectivity.

Tip

See also:

←  $neLogical Query Operators →

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