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Articles by AmitDiwan
Page 574 of 840
How to merge multiple documents in MongoDB?
To merge multiple documents in MongoDB, use the aggregate() method with operators like $group and $push to combine data from documents that share common fields. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $group: { _id: "$groupingField", mergedArray: { $push: "$arrayField" }, sumField: { $sum: "$numericField" } }} ]); Sample Data db.demo436.insertMany([ { ...
Read MoreHow to append to array in MongoDB?
To append to array in MongoDB, use the $concatArrays operator in aggregation pipelines to combine multiple arrays into a single array. This operator concatenates arrays and returns the combined result. Syntax db.collection.aggregate([ { $project: { newField: { $concatArrays: ["$array1", "$array2", ...] } ...
Read MoreMongoDB aggregation / math operation to sum score of a specific student
To sum scores of a specific student in MongoDB, use the aggregate() method with $match to filter by student name and $sum to calculate the total score. Syntax db.collection.aggregate([ { "$match": { "Name": "StudentName" } }, { "$group": { "_id": null, "TotalScore": { "$sum": "$Score" } } } ]); Sample Data db.demo434.insertMany([ {"Name": "Chris", "Score": 45}, {"Name": "David", "Score": 55}, {"Name": "Chris", "Score": 55} ]); { ...
Read MoreHow 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": ...
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