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$ne (expression operator)

Definition

$ne

Compares two values and returns:

true when the values are not equivalent.
false when the values are equivalent.

If a field is missing from a document, $ne treats the missing field as a distinct value, separate from null. $ne considers two missing fields equivalent to each other, and considers a missing field different from a null value.

The $ne compares both value and type, using the specified BSON comparison order for values of different types.

$ne has the following syntax:

{ $ne: [ <expression1>, <expression2> ] }

For more information on expressions, see Expressions.

Example

Consider an inventory collection with the following documents:

db.inventory.insertMany( [
   { _id: 1, item: "abc1", description: "product 1", qty: 300 }
   { _id: 2, item: "abc2", description: "product 2", qty: 200 }
   { _id: 3, item: "xyz1", description: "product 3", qty: 250 }
   { _id: 4, item: "VWZ1", description: "product 4", qty: 300 }
   { _id: 5, item: "VWZ2", description: "product 5", qty: 180 }
] )

The following operation uses the $ne operator to determine if qty does not equal 250:

db.inventory.aggregate(
   [
     {
       $project:
          {
            item: 1,
            qty: 1,
            qtyNe250: { $ne: [ "$qty", 250 ] },
            _id: 0
          }
     }
   ]
)

The operation returns the following results:

{ item: "abc1", qty: 300, qtyNe250: true }
{ item: "abc2", qty: 200, qtyNe250: true }
{ item: "xyz1", qty: 250, qtyNe250: false }
{ item: "VWZ1", qty: 300, qtyNe250: true }
{ item: "VWZ2", qty: 180, qtyNe250: true }

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