Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
MongoDB Articles
Page 36 of 111
Ignore NULL and UNDEFINED values while running a MongoDB query
To ignore NULL and UNDEFINED values while querying in MongoDB, use the $ne (not equal) operator. This operator excludes documents where the specified field is null or undefined. Syntax db.collection.find({"fieldName": {$ne: null}}) Create Sample Data db.demo35.insertMany([ {"Name": "Chris"}, {"Name": null}, {"Name": "Bob"}, {"Name": undefined} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e175e42cfb11e5c34d898d0"), ...
Read MoreMongoDB query to find on the basis of true or false values
To find documents based on true or false values in MongoDB, use the $exists operator with dot notation to check field presence or use direct boolean value matching. Syntax db.collection.find({"field": { $exists: true/false }}); db.collection.find({"booleanField": true/false}); Sample Data db.demo367.insertMany([ { "Id": "102", "details": [ { "Name": "David" }, { ...
Read MoreMongoDB query to update a MongoDB row with only the objectid
To update a MongoDB document using only its ObjectId, use the update() method with the _id field as the query filter and the $set operator to modify specific fields. Syntax db.collection.update( { "_id": ObjectId("objectid_value") }, { $set: { "field1": "new_value1", "field2": "new_value2" } } ); Sample Data Let us create a collection with sample documents ? db.demo34.insertMany([ { "StudentFirstName": "Chris", "StudentAge": 24 }, { "StudentFirstName": "David", "StudentAge": 23 }, { "StudentFirstName": "Bob", ...
Read MoreMongoDB aggregation framework to sort by length of array?
To sort documents by the length of an array field in MongoDB, use the aggregation framework with $addFields and $size operators to calculate array lengths, then sort by the computed field. Syntax db.collection.aggregate([ { $addFields: { arrayLength: { $size: "$arrayField" } } }, { $sort: { arrayLength: -1 } } ]); Sample Data db.demo33.insertMany([ { "ListOfStudent": ["Chris", "Bob"] }, { "ListOfStudent": ["David", "Adam", "Mike"] }, { "ListOfStudent": ["Carol", "Sam", "John", "Robert"] } ]); ...
Read MoreHow to compare attributes of different objects in MongoDB object array?
To compare attributes of different objects in a MongoDB object array, use $let along with $indexOfArray to locate specific array elements and compare their values using comparison operators. Syntax db.collection.find({ "$expr": { "$let": { "vars": { "element1": {"$arrayElemAt": ["$arrayName", {"$indexOfArray": ["$arrayName.field", "value1"]}]}, ...
Read MoreHow to force MongoDB to use the BasicCursor instead of an index?
To force MongoDB to use a BasicCursor instead of an index, use the hint() method with $natural: 1. This bypasses any existing indexes and performs a collection scan in natural document order. Syntax db.collection.find(query).hint({ $natural: 1 }); Create Sample Data First, let's create an index and insert some test documents ? db.demo31.createIndex({"StudentFirstName": 1}); { "createdCollectionAutomatically": true, "numIndexesBefore": 1, "numIndexesAfter": 2, "ok": 1 } db.demo31.insertMany([ {"StudentFirstName": "John"}, ...
Read MoreMongoDB query to find a specific city record from a collection
To find a specific city record from a MongoDB collection, use the find() method with a query document that matches the desired city name. This allows you to retrieve documents based on specific field values. Syntax db.collection.find({"fieldName": "value"}); Sample Data Let us create a collection with city documents ? db.demo30.insertMany([ {"City": "New York"}, {"City": "Los Angeles"}, {"City": "Chicago"}, {"City": "Los Angeles"} ]); { "acknowledged": true, ...
Read MoreGet array items inside a MongoDB document?
To get array items in a MongoDB document, use the dot (.) notation to access fields within array elements. This allows you to query documents based on values inside arrays and retrieve specific array items. Syntax db.collection.find({"arrayName.fieldName": "value"}); Sample Data db.demo29.insertMany([ { "StudentDetails": [ {"StudentName": "Chris", "StudentMarks": 58}, {"StudentName": "Bob", "StudentMarks": 69} ...
Read MoreCan we use the "." symbol in MongoDB collection name?
Yes, we can use the "." symbol in MongoDB collection names. However, you must use the getCollection() method to access collections containing dots, as the standard dot notation would be interpreted as nested properties. Syntax db.getCollection('collection.name.with.dots') Example: Creating and Using Collection with Dots Let's create a collection named "demo28.example" and insert documents ? db.getCollection('demo28.example').insertMany([ {"Name": "Chris", "Age": 32}, {"Name": "Bob", "Age": 31}, {"Name": "David", "Age": 33} ]); { "acknowledged": true, ...
Read MoreIs it possible to utilize $addToSet multiple times in the same update?
Yes, it is possible to use $addToSet multiple times in the same update operation. You can specify multiple fields or use the $each modifier to add multiple values to the same array in a single operation. Syntax // Multiple $addToSet operations db.collection.update( { query }, { $addToSet: { "field1": "value1", "field2": "value2" ...
Read More