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
Articles on Trending Technologies
Technical articles with clear explanations and examples
How to filter a query on specific date format with MongoDB?
To filter a query on specific date format in MongoDB, use the $dateToString operator within an aggregation pipeline to convert dates to string format and then match against the desired date pattern. Syntax db.collection.aggregate([ { $addFields: { stringDate: { $dateToString: { format: "%Y-%m-%d", date: "$dateField" } } } }, { $match: { "stringDate": "YYYY-MM-DD" } }, { $project: { "stringDate": 0 } } ]); Sample Data db.demo433.insertMany([ { "DueDate": new Date("2019-11-23") }, { ...
Read MoreAggregation framework to get the name of students with test one score less than the total average of all the tests
To find students whose test one score is less than the total average of all tests, use MongoDB's aggregation framework with $project, $group, $filter, and $map operators to calculate averages and filter results. Syntax db.collection.aggregate([ { $project: { Name: 1, Value1: 1, average: { $avg: ["$Value1", "$Value2", "$Value3"] } } }, { $group: { _id: null, students: { $push: {Name: "$Name", Value1: "$Value1"} }, totalAverage: { $avg: "$average" } } }, { $project: { filteredNames: { $map: { input: { $filter: { input: "$students", cond: ...
Read MoreWhat is the fastest way to update the whole document (all fields) in MongoDB?
The fastest way to update the whole document (all fields) in MongoDB is to use replaceOne() method. This method replaces the entire document while preserving the _id field. Syntax db.collection.replaceOne( { filter }, { newDocument } ); Sample Data db.demo431.insertMany([ {"Name": "Chris", "Age": 32}, {"Name": "David", "Age": 31}, {"Name": "John", "Age": 24}, {"Name": "Bob", "Age": 22} ]); { "acknowledged": true, ...
Read MoreMongoDB query to group records and display a specific value with dot notation
To group records in MongoDB and display specific values using dot notation, use the $group aggregation stage with field references like "$details.Name" to extract values from nested documents or arrays. Syntax db.collection.aggregate([ { $group: { "_id": { "fieldName": "$arrayField.nestedField" } } } ]); Sample Data db.demo430.insertOne({ "details": [ ...
Read MoreMongoDB query to create new field and count set the count of another field in it?
To create a new field and count elements from another field in MongoDB, use $addFields with $map and $size operators. This allows you to transform array elements and count their sizes in a single aggregation. Syntax db.collection.aggregate([ { "$addFields": { "arrayField": { "$map": { ...
Read MoreConditional upsert (multiple insert) when updating document in MongoDB?
To perform conditional upserts and multiple inserts when updating documents in MongoDB, use the bulkWrite() method. This allows you to combine update operations and insert operations in a single transaction-like operation. Syntax db.collection.bulkWrite([ { "updateOne": { "filter": { field: value }, "update": { $set: { newField: newValue } } }}, { "insertOne": { "document": { field1: value1, field2: value2 } ...
Read MoreUpdate a MongoDB document with Student Id and Name
To update a MongoDB document with Student Id and Name, use the update() method with $set operator. The $set operator modifies specific fields without affecting other document properties. Syntax db.collection.update( { "field": "matchValue" }, { $set: { "field": "newValue" } } ); Sample Data Let us create a collection with student documents : db.demo427.insertMany([ { "StudentId": 101, "StudentName": "Chris Brown" }, { "StudentId": 102, "StudentName": "David Miller" }, { "StudentId": 103, "StudentName": ...
Read MoreMatch ID and fetch documents with $eq in MongoDB in case of array?
Use the $eq operator along with find() to match ID values within arrays and fetch documents. The $eq specifies an equality condition and matches documents where any array element equals the specified value. Syntax db.collection.find({"arrayField": {$eq: "value"}}); // Alternative (equivalent) syntax db.collection.find({"arrayField": "value"}); Sample Data Let us create a collection with documents ? db.demo426.insertMany([ {"Ids": ["110", "120", "101"]}, {"Ids": ["100", "201", "401"]}, {"Ids": ["501", "600", "700"]} ]); { "acknowledged": true, ...
Read MoreUpsert many documents in MongoDB
To upsert many documents in MongoDB, use bulk operations with the upsert() option. This allows you to update multiple documents if they exist, or insert new ones if they don't match the query criteria. Syntax var bulk = db.collection.initializeUnorderedBulkOp(); bulk.find({queryCondition}).upsert().update({ $setOnInsert: {fieldsForNewDocuments}, $set: {fieldsToUpdate} }); bulk.execute(); Sample Data Let us create a collection with duplicate documents − db.demo425.insertMany([ {"Name": "Chris", "Age": 21}, {"Name": "David", "Age": 23}, {"Name": "Chris", "Age": 21}, ...
Read MoreExtract a MongoDB document with a specific string
To extract a MongoDB document with a specific string, use the $match operator in an aggregation pipeline to filter documents containing the target string value. Syntax db.collection.aggregate([ { $match: { "field": "specific_string" } } ]); Create Sample Data db.demo424.insertMany([ { "Information": [ { id: 10, ...
Read More