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Comparison query operators allow you to compare the elements in a document to a given query value.
Go to the comparison query operators:
| Operator | Description |
|---|---|
$eq |
Selects documents with elements that are equal to a given query value |
$gt |
Selects documents with elements that are greater than a given query value |
$gte |
Selects documents greater than or equal to specified query |
$lt |
Selects documents with elements that are less than a given query value |
$lte |
Selects documents with elements less than or equal to given query value |
$in |
Selects documents that contain the elements in a given array query |
$ne |
Selects documents with elements that are not equal to given query value |
$nin |
Selects documents that do not contain the elements in a given array query |
For the examples in this section, insert the following documents into the employees collection:
db.employees.insertMany([
{
name: {
first: 'Earl',
last: 'Thomas'
},
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
},
{
name: {
first: 'Sam',
last: 'Johnson'
},
employeeID: 2234,
age: 35,
role: 'salesperson',
catalog: ['cabinet', 'fridge', 'blender', 'utensils']
},
{
name: {
first: 'Clarke',
last: 'Dane'
},
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
])Syntax: { <field>: { $eq: <element> } }
To select documents that exactly match a given query value, use the $eq operator.
This operator can be used to match values of different types, including documents, array, embedded documents, etc.
Example: The following operation queries the employees collection for all documents where the field age equals 21.
db.employees.find({
age: {
$eq: 21
}
})The response returns a single document that matches the query:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0e"),
name: { first: 'Clarke', last: 'Dane' },
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
]Example: To query values in an embedded document, use dot notation.
The following operation queries the employees collection for documents that match the field first in the embedded document name.
db.employees.find({
'name.first': {
$eq: 'Earl'
}
})The response returns a single document that matches the query:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
}
]Syntax: { <field>: { $gt: <element> } }
To identify documents containing elements that have a greater value than the specified one in the query, use the $gt operator.
Example: Use the following operation to query for all the documents in the employees collection where the field age is greater than 21.
db.employees.find({
age: {
$gt: 21
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0d"),
name: { first: 'Sam', last: 'Johnson' },
employeeID: 2234,
age: 35,
role: 'salesperson',
catalog: ['cabinet', 'fridge', 'blender', 'utensils']
}
]Syntax: { <field>: { $gte: <element> } }
Use the $gte to select document with elements that are greater than or equal to a specified value.
Example: The following operation selects documents based on the specified query, where the field age is greater than or equal to 21.
db.employees.find({
age: {
$gte: 21
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0d"),
name: { first: 'Sam', last: 'Johnson' },
employeeID: 2234,
age: 35,
role: 'salesperson',
catalog: ['cabinet', 'fridge', 'blender', 'utensils']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0e"),
name: { first: 'Clarke', last: 'Dane' },
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
]Syntax: { <field>: { $lt: <element> } }
Contrary to the $gt operator, the $lt operator is ideal for selecting documents with elements that are of a lesser value than that of the specified query.
Example: The following operation queries for documents where the field age is less than 25.
db.employees.find({
age: {
$lt: 25
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0e"),
name: { first: 'Clarke', last: 'Dane' },
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
]Syntax: { <field>: { $lte: <element> } }
The $lte operator is the opposite of the $gte operator.
Use the $lte operator to select documents with elements that are less than or equal to the specified query value.
Example: The following operation queries for documents where the field age is less than or equal to 21.
db.employees.find({
age: {
$lte: 21
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0e"),
name: { first: 'Clarke', last: 'Dane' },
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
]Syntax: { <field>: { $in: [<element1>, <element2>, ... <elementN> ] } }
To select documents containing any of the listed elements in a specified array field, use the $in operator.
Example: The following operation queries the employees collection for documents where the value of the field age is either 21 or 35.
db.employees.find({
age: {
$in: [21, 35]
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0d"),
name: { first: 'Sam', last: 'Johnson' },
employeeID: 2234,
age: 35,
role: 'salesperson',
catalog: ['cabinet', 'fridge', 'blender', 'utensils']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0e"),
name: { first: 'Clarke', last: 'Dane' },
employeeID: 3234,
age: 21,
role: 'salesperson',
catalog: ['printer', 'pencils', 'crayons', 'toys']
}
]Syntax: { <field>: { $ne: <element> } }
Use the $ne operator to select all the documents with elements that are not equal to a given query.
Example: The following operation queries the employees collection for documents where the field age is not equal to 21.
db.employees.find({
age: {
$ne: 21
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
},
{
_id: ObjectId("639a3cce071b6bed396a8f0d"),
name: { first: 'Sam', last: 'Johnson' },
employeeID: 2234,
age: 35,
role: 'salesperson',
catalog: ['cabinet', 'fridge', 'blender', 'utensils']
}
]Syntax: { <field>: { $nin: [ <element1>, <element2> ... <elementN> ] } }
The $nin does exactly the opposite of the $in operator.
Use the $nin operator when selecting documents that do match or contain any of the elements listed in an array query.
Example: The following operation queries the employees collection for documents where the value of the field age is not 21 or 35.
db.employees.find({
age: {
$nin: [21, 35]
}
})The output:
[
{
_id: ObjectId("639a3cce071b6bed396a8f0c"),
name: { first: 'Earl', last: 'Thomas' },
employeeID: 1234,
age: 23,
role: 'salesperson',
catalog: ['printer', 'cardboard', 'crayons', 'books']
}
]