MongoDB – Comparison Query Operators

MongoDB uses various comparison query operators to compare the values of the documents. The following table contains the comparison query operators:

Operators	Description
$eq	It is used to match the values of the fields that are equal to a specified value.
$ne	It is used to match all values of the field that are not equal to a specified value.
$gt	It is used to match values of the fields that are greater than a specified value.
$gte	It is used to match values of the fields that are greater than equal to the specified value.
$lt	It is used to match values of the fields that are less than a specified valueo
$lte	It is used to match values of the fields that are less than equals to the specified value
$in	It is used to match any of the values specified in an array.
$nin	It is used to match none of the values specified in an array.

In the following examples, we are working with:

Database: GeeksforGeeks
Collection: contributor
Document: three documents that contain the details of the contributors in the form of field-value pairs.

Matching values using $nin operator:

In this example, we are retrieving only those employee’s documents whose name is not Amit or Suman.

db.contributor.find({name: {$nin: ["Amit", "Suman"]}}).pretty()

Matching values using $in operator:

In this example, we are retrieving only those employee’s documents whose name is either Amit or Suman.

db.contributor.find({name: {$in: ["Amit", "Suman"]}}).pretty()

Matching values using $lt operator:

In this example, we are selecting those documents where the value of the salary field is less than 2000.

db.contributor.find({salary: {$lt: 2000}}).pretty()

Matching values using $eq operator:

In this example, we are selecting those documents where the value of the branch field is equal to CSE.

db.contributor.find({branch: {$eq: "CSE"}}).pretty()

Matching values using $ne operator:

In this example, we are selecting those documents where the value of the branch field is not equal to CSE.

db.contributor.find({branch: {$ne: "CSE"}}).pretty()

Matching values using $gt operator:

In this example, we are selecting those documents where the value of the salary field is greater than 1000.

db.contributor.find({salary: {$gt: 1000}}).pretty()

Matching values using $gte operator:

In this example, we are selecting those documents where the value of the joiningYear field is greater than equals to 2017.

db.contributor.find({joiningYear: {$gte: 2017}})

Matching values using $lte operator:

In this example, we are selecting those documents where the value of the salary field is less than equals to 1000.

db.contributor.find({salary: {$lte: 1000}}).pretty()