MongoDB $lt

Summary: in this tutorial, you will learn how to use the MongoDB $lt operator to select documents where the value of a field is less than (<) a specified value.

Introduction to the MongoDB $lt operator

The $lt operator is a comparison query operator that allows you to select the documents where the value of a field is less than a specified value.

Here is the syntax of the $lt operator:

{field: {$lt: value} }
Code language: CSS (css)

MongoDB $lt operator examples

We’ll use the following products collection:

db.products.insertMany([ { "_id" : 1, "name" : "xPhone", "price" : 799, "releaseDate": ISODate("2011-05-14"), "spec" : { "ram" : 4, "screen" : 6.5, "cpu" : 2.66 },"color":["white","black"],"storage":[64,128,256]}, { "_id" : 2, "name" : "xTablet", "price" : 899, "releaseDate": ISODate("2011-09-01") , "spec" : { "ram" : 16, "screen" : 9.5, "cpu" : 3.66 },"color":["white","black","purple"],"storage":[128,256,512]}, { "_id" : 3, "name" : "SmartTablet", "price" : 899, "releaseDate": ISODate("2015-01-14"), "spec" : { "ram" : 12, "screen" : 9.7, "cpu" : 3.66 },"color":["blue"],"storage":[16,64,128]}, { "_id" : 4, "name" : "SmartPad", "price" : 699, "releaseDate": ISODate("2020-05-14"),"spec" : { "ram" : 8, "screen" : 9.7, "cpu" : 1.66 },"color":["white","orange","gold","gray"],"storage":[128,256,1024]}, { "_id" : 5, "name" : "SmartPhone", "price" : 599,"releaseDate": ISODate("2022-09-14"), "spec" : { "ram" : 4, "screen" : 9.7, "cpu" : 1.66 },"color":["white","orange","gold","gray"],"storage":[128,256]} ])
Code language: JavaScript (javascript)

1) Using $lt operator to select documents where a field is less than a specified value

The following example uses the $lt operator to select documents from the products collection where price is less than 799:

db.products.find({ price: { $lt: 799 } }, { name: 1, price: 1 })
Code language: CSS (css)

Output:

{ "_id" : 4, "name" : "SmartPad", "price" : 699 } { "_id" : 5, "name" : "SmartPhone", "price" : 599 }
Code language: JSON / JSON with Comments (json)

2) Using the $lt operator to check if a field in an embedded document is less than a value

The following query uses $lt operator to select documents where the value of the screen field in the spec document is less than 7:

db.products.find({ "spec.screen": { $lt: 7 } }, { name: 1, "spec.screen": 1 })
Code language: PHP (php)

Output:

{ "_id" : 1, "name" : "xPhone", "spec" : { "screen" : 6.5 } } { "_id" : 5, "name" : "SmartPhone", "spec" : { "screen" : 5.7 } }
Code language: JSON / JSON with Comments (json)

3) Using the $lt operator to check if an array element is greater than or equal to a value

The following example uses the $lt operator to query the products collection to find all documents where the array storage has at least one element less than 128:

db.products.find({ storage: { $lt: 128 } }, { name: 1, storage: 1 })
Code language: CSS (css)

The query returned the following documents:

{ "_id" : 1, "name" : "xPhone", "storage" : [ 64, 128, 256 ] } { "_id" : 3, "name" : "SmartTablet", "storage" : [ 16, 64, 128 ] }
Code language: JSON / JSON with Comments (json)

4) Using the $lt operator to check if a field is before a date

The following query uses the $lt operator to select documents from the products collection to find all documents where the release date before 2015-01-01:

db.products.find({ "releaseDate": { $lt: new ISODate('2015-01-01') } }, { name: 1, releaseDate: 1 })
Code language: PHP (php)

The query returned the following documents:

{ "_id" : 1, "name" : "xPhone", "releaseDate" : ISODate("2011-05-14T00:00:00Z") } { "_id" : 2, "name" : "xTablet", "releaseDate" : ISODate("2011-09-01T00:00:00Z") }
Code language: JSON / JSON with Comments (json)

Summary

  • Use the $lt operator to select documents where a field is less a specified value.
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