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Articles on Trending Technologies
Technical articles with clear explanations and examples
MongoDB 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 MoreGet execution stats in MongoDB for a collection
To get execution stats in MongoDB for a collection, use the explain() method with "executionStats" parameter. This provides detailed performance information about query execution including execution time and documents examined. Syntax db.collection.find(query).explain("executionStats"); Sample Data db.demo157.insertMany([ {"Status": "Active"}, {"Status": "InActive"} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e354fdffdf09dd6d08539fc"), ObjectId("5e354fe3fdf09dd6d08539fd") ] } Display all documents ...
Read MoreHow to sort by the difference in array contents in MongoDB?
To sort by the difference in array contents, use MongoDB's aggregation pipeline with $project to calculate differences and $sort to order results. This is useful when comparing values between array elements. Syntax db.collection.aggregate([ { $project: { "fieldName": "$fieldName", "difference": { $subtract: [ { $arrayElemAt: ["$arrayField", index1] }, ...
Read MoreQuery a nested field within an array with MongoDB
To query a nested field within an array in MongoDB, use the $elemMatch operator to match documents where at least one array element satisfies all specified query criteria. Syntax db.collection.find({ "arrayField": { "$elemMatch": { "nestedField": "value" } } }); Sample Data Let us create a collection with documents containing nested arrays ? ...
Read MoreMongoDB query to update an array using FindAndUpdate()?
To update an array in MongoDB, use the findAndModify() method combined with the $ positional operator to target specific array elements. This method updates the document and returns either the original or updated version. Syntax db.collection.findAndModify({ query: { "arrayField": "matchValue" }, update: { $set: { "arrayField.$": "newValue" } } }); Sample Data db.demo152.insertMany([ {"id": 102, "Name": ["Chris", "David"], "Score": 45}, {"id": 103, "Name": ["Mike", "Carol"], "Score": 65} ]); { "acknowledged": ...
Read MoreMongoDB projection result as an array of selected items?
In MongoDB, projection results as an array of selected items can be achieved using the distinct() method. This method returns an array of distinct values for a specified field from documents that match the given query criteria. Syntax db.collection.distinct(field, query) Where field is the field to return distinct values from, and query is the optional filter criteria. Sample Data Let us create a collection with documents: db.demo151.insertMany([ {"ListOfNames": ["Chris", "David", "Mike"]}, {"ListOfNames": ["Mike", "Bob"]}, {"ListOfNames": ["John", "David", "Chris"]} ]); ...
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