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Database Articles
Page 36 of 547
Update values in multiple documents with multi parameter in MongoDB?
To update values in multiple documents in MongoDB, use the multi: true parameter in the update operation. By default, MongoDB updates only the first matching document, but setting multi: true updates all documents that match the query criteria. Syntax db.collection.update( { query }, { $set: { field: "newValue" } }, { multi: true } ); Sample Data Let us create a collection with sample documents ? db.demo390.insertMany([ { "FirstName": "Chris" }, { ...
Read MoreExtract all the values and display in a single line with MongoDB
To extract all values from nested arrays and display them in a single line in MongoDB, use the $unwind operator to flatten arrays and $group with $push to combine all values into one array. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $unwind: "$arrayField.nestedArray" }, { $group: { _id: null, result: { $push: "$arrayField.nestedArray" } } } ]); Sample Data db.demo389.insertOne({ "details": [ { "Name": ["Chris", "David"] }, ...
Read MoreMongoDB query to remove element from array as sub property
To remove an element from an array that exists as a sub-property in MongoDB, use the $pull operator with dot notation to target the nested array field. Syntax db.collection.update( { "matchField": "matchValue" }, { "$pull": { "parentField.arrayField": { "field": "valueToRemove" } } } ); Sample Data Let us first create a collection with documents ? db.demo388.insertOne({ _id: '101', userDetails: { isMarried: false, ...
Read MoreMongoDB query to unwind two arrays
To unwind two arrays in MongoDB, use multiple $unwind stages in an aggregation pipeline. This deconstructs each array field to create separate documents for every combination of array elements. Syntax db.collection.aggregate([ { "$unwind": "$arrayField1" }, { "$unwind": "$arrayField2" }, { "$match": { /* optional filtering */ } } ]) Sample Data db.demo387.insertOne({ "Name": "101", "Details1": [ {Value: 100, Value1: 50, Value2: 40}, ...
Read MoreConvert date parts to date in MongoDB
To convert separate date parts (year, month, day) into a complete date in MongoDB, use the $dateFromParts operator within an aggregation pipeline. This operator combines individual date components into a proper date object. Syntax db.collection.aggregate([ { $project: { dateField: { $dateFromParts: { ...
Read MoreUpdate multiple elements in an array in MongoDB?
To update multiple elements in an array in MongoDB, use the $[] all positional operator. This operator modifies all elements in the specified array field that match the update criteria. Syntax db.collection.update( { "matchCondition": "value" }, { $set: { "arrayField.$[]": "newValue" } } ); Sample Data Let us first create a collection with documents ? db.demo385.insertOne({ "ServerLogs": [ { "status": ...
Read MoreDisplay only a single field from all the documents in a MongoDB collection
To display only a single field from all documents in a MongoDB collection, use projection in the find() method. Set the desired field to 1 to include it, or set unwanted fields to 0 to exclude them. Syntax db.collection.find({}, {fieldName: 1, _id: 0}); // OR db.collection.find({}, {unwantedField1: 0, unwantedField2: 0}); Sample Data db.demo384.insertMany([ {"StudentName": "Chris Brown", "StudentCountryName": "US"}, {"StudentName": "David Miller", "StudentCountryName": "AUS"}, {"StudentName": "John Doe", "StudentCountryName": "UK"} ]); { "acknowledged": true, ...
Read MoreMongoDB query to filter only the logs containing the "work" word in the content
To filter logs containing the word "work" in MongoDB, use the $filter operator with $indexOfBytes to perform case-insensitive substring matching within an aggregation pipeline. Syntax db.collection.aggregate([ { "$addFields": { "arrayField": { "$filter": { "input": "$arrayField", ...
Read MoreMongoDB aggregate $slice to get the length of the array
To get the length of an array in MongoDB using aggregation, use the $size operator within a $project stage. The $size operator returns the number of elements in the specified array field. Syntax db.collection.aggregate([ { $project: { "fieldName": { $size: "$arrayField" } } } ]); Sample Data Let us create a collection with documents ? db.demo382.insertOne({ "Name": "David", "details": [ { ...
Read MoreHow to search an array for values present in another array and output the indexes of values found into a new array in MongoDB?
To search an array for values present in another array and output the indexes of values found into a new array in MongoDB, use the $indexOfArray operator combined with $map within an aggregation pipeline. Syntax db.collection.aggregate([ { "$project": { "Result": { "$map": { ...
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