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
Big Data Analytics Articles
Page 42 of 135
MongoDB query to insert an array element with a condition?
To insert an array element with a condition in MongoDB, use the $push operator combined with the $ positional operator to add new elements to nested arrays when specific conditions are met. Syntax db.collection.update( {"arrayField.conditionField": "value"}, {$push: {"arrayField.$.targetArray": newElement}} ); Sample Data db.demo11.insertOne({ "ListOfStudent": [ { "StudentName": "Chris", "ListOfScore": ...
Read MoreMongoDB query for a single field
To query a single field in MongoDB, use the find() method with projection. Projection allows you to specify which fields to include or exclude from the query results. Syntax db.collection.find({}, { "fieldName": 1, "_id": 0 }); Sample Data Let us first create a collection with documents ? db.demo10.insertMany([ { "StudentId": 101, "StudentName": "Chris" }, { "StudentId": 102, "StudentName": "David" }, { "StudentId": 103, "StudentName": "Bob" } ]); { "acknowledged": true, ...
Read MoreHow to get a "-Infinity" result for $avg in an aggregate query?
In MongoDB aggregation, the $avg operator returns -Infinity when calculating the average of values that include -Infinity. This occurs because any arithmetic operation involving -Infinity propagates the infinite value. Syntax db.collection.aggregate([ { $group: { "_id": "$groupField", "average": { $avg: "$numericField" } } } ]); Sample Data ...
Read MoreIs MongoDB able to index a null value?
Yes, MongoDB can index null values. When you create an index on a field, MongoDB includes documents where that field is null or missing in the index. This allows efficient queries on null values using the index. Syntax db.collection.createIndex({"fieldName": 1}) db.collection.find({"fieldName": null}) Create Sample Data First, create a unique index on the "Value" field and insert documents with null values ? db.demo170.createIndex({"Value": 1}, {unique: true}); { "createdCollectionAutomatically": true, "numIndexesBefore": 1, "numIndexesAfter": 2, "ok": 1 } db.demo170.insertMany([ ...
Read MoreFetch all the ids of MongoDB documents?
To fetch all the document IDs from a MongoDB collection, use the find() method with projection to return only the _id field by excluding other fields. Syntax db.collection.find({}, {"fieldName": 0}); // OR db.collection.find({}, {"_id": 1}); Sample Data Let us create a collection with sample documents ? db.demo169.insertMany([ {"StudentName": "Chris"}, {"StudentName": "Bob"}, {"StudentName": "David"} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e36975e9e4f06af551997d7"), ...
Read MoreMongoDB query to return only specific fields (phone numbers) in the form of an array?
To return only specific fields (phone numbers) as an array in MongoDB, use the distinct() method to extract unique values from nested fields across all documents in a collection. Syntax db.collection.distinct("field.path") Sample Data Let us create a collection with documents − db.demo166.insertMany([ { "details": { "UserName": "Chris", "UserAge": 29, ...
Read MoreMongoDB query with $all in array
In MongoDB, the $all operator is used to select documents where the value of a field is an array that contains all the specified elements. This operator matches documents where the array field contains every element listed in the $all array, regardless of order or additional elements. Syntax db.collection.find({ "arrayField": { $all: [element1, element2, ...] } }); Create Sample Data Let us create a collection with documents containing client details ? db.demo163.insertMany([ { "ClientDetails": [ ...
Read MoreUpdating a MongoDB document and adding new keys only in the first document?
To update a MongoDB document and add new keys only to the first document in a collection, use the update() method with an empty query filter and $set operator. This targets the first document that matches the query criteria. Syntax db.collection.update( {}, { $set: { "newField": "value" } }, { upsert: true } ); Sample Data db.demo162.insertMany([ { "StudentName": "Chris" }, { "StudentName": "Bob" }, { "StudentName": "David" } ...
Read MoreSearch for multiple documents in MongoDB?
To search for multiple documents in MongoDB, use the $in operator to match documents where a field value equals any value in a specified array. This allows you to retrieve multiple documents with a single query instead of running separate queries for each value. Syntax db.collection.find({ "fieldName": { $in: [value1, value2, value3, ...] } }); Sample Data Let us create a collection with sample client documents ? db.demo161.insertMany([ {"ClientId": 101, "ClientName": "Chris"}, {"ClientId": 102, "ClientName": "David"}, ...
Read MoreGroupBy Date in MongoDB to count duplicate date records
To count duplicate date records in MongoDB, use the aggregate() method with $group to group documents by date and count occurrences. Syntax db.collection.aggregate([ { $group: { _id: "$dateField", count: { $sum: 1 } } }, { $match: ...
Read More