$exists
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Definition
-
$exists
-
Syntax:
{ field: { $exists: <boolean> } }
When
<boolean>
is true,$exists
matches the documents that contain the field, including documents where the field value isnull
. If<boolean>
is false, the query returns only the documents that do not contain the field.MongoDB $exists does not correspond to SQL operator
exists
. For SQLexists
, refer to the$in
operator.
See also
Examples
Exists and Not Equal To
Consider the following example:
This query will select all documents in the inventory
collection where the qty
field exists and its value does not equal 5
or 15
.
Null Values
The following examples uses a collection named records
with the following documents: