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} }
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]}
])
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
})
Output:
{ "_id" : 4, "name" : "SmartPad", "price" : 699 }
{ "_id" : 5, "name" : "SmartPhone", "price" : 599 }
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
})
Output:
{ "_id" : 1, "name" : "xPhone", "spec" : { "screen" : 6.5 } }
{ "_id" : 5, "name" : "SmartPhone", "spec" : { "screen" : 5.7 } }
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
})
The query returned the following documents:
{ "_id" : 1, "name" : "xPhone", "storage" : [ 64, 128, 256 ] }
{ "_id" : 3, "name" : "SmartTablet", "storage" : [ 16, 64, 128 ] }
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
})
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") }
Summary
- Use the
$lt
operator to select documents where a field is less a specified value.