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Big Data Analytics Articles
Page 107 of 135
Check that Field Exists with MongoDB?
In MongoDB, you can check if a field exists in documents using the $exists operator. To ensure the field is not null, combine it with the $ne operator. Syntax db.collection.find({ "fieldName": { $exists: true, $ne: null } }) Sample Data db.checkFieldExistDemo.insertMany([ { "EmployeeId": 1, "EmployeeName": "John", "isMarried": true, "EmployeeSalary": 4648585 }, ...
Read MoreGet MongoDB documents with max attribute per group in a collection?
To get documents with the maximum attribute per group in a MongoDB collection, use the $sort operator combined with the $group stage in an aggregation pipeline. This approach sorts documents by the grouping field and the target attribute, then uses $first to select the document with the highest value per group. Sample Data db.maxAttributePerGroup.insertMany([ { "StudentFirstName": "John", "StudentLastName": "Smith", "StudentAge": 29, ...
Read MoreHow to replace substring in MongoDB document?
In MongoDB, you can replace substrings in documents using JavaScript's replace() function within a forEach() loop. This approach finds documents, modifies the substring, and updates them back to the collection. Sample Data db.replaceSubstringDemo.insertOne({ "WebsiteURL": "www.gogle.com" }); { "acknowledged": true, "insertedId": ObjectId("5c76eaf21e9c5dd6f1f78276") } Let's verify the document was inserted ? db.replaceSubstringDemo.find().pretty(); { "_id": ObjectId("5c76eaf21e9c5dd6f1f78276"), "WebsiteURL": "www.gogle.com" } Replace Substring Using forEach() To replace "gogle" with ...
Read MoreGet a count of total documents with MongoDB while using limit?
To get a count of total documents while also limiting the results, use the $facet operator in MongoDB. This allows you to run multiple aggregation pipelines on the same data simultaneously − one for the limited data and another for the total count. Syntax db.collection.aggregate([ { $facet: { data: [{ $limit: number }], totalCount: [{ $count: "total" }] ...
Read MoreMongoDB Regex Search on Integer Value?
To perform regex search on integer values in MongoDB, use the $where operator with JavaScript regex testing. This allows pattern matching on numeric fields by converting them to strings during evaluation. Syntax db.collection.find({ $where: "/^yourPattern.*/.test(this.fieldName)" }); Sample Data db.regExpOnIntegerDemo.insertMany([ { "StudentId": 2341234 }, { "StudentId": 123234 }, { "StudentId": 9871234 }, { "StudentId": 2345612 }, { "StudentId": 1239812345 } ]); { ...
Read MoreHow to sort inner array in MongoDB?
To sort inner arrays in MongoDB, use the aggregation framework with $unwind, $sort, $group, and $project stages. This approach deconstructs the array, sorts the elements, and reconstructs the sorted array. Sample Data db.sortInnerArrayDemo.insertOne({ "EmployeeDetails": { "EmployeeAddress": { "EmployeeCountry": [ { ...
Read MoreQuerying internal array size in MongoDB?
To query internal array size in MongoDB, use the $size operator. This operator returns the number of elements in an array field and can be used within aggregation pipelines to count array elements for specific documents. Syntax db.collection.aggregate([ { $group: { _id: yourObjectIdValue, fieldName: { $first: { $size: "$arrayFieldName" } } } ...
Read MoreAdd new field to every document in a MongoDB collection?
To add new field to every document in a MongoDB collection, you can use $set operator. The syntax is as follows ? Syntax db.yourCollectionName.update({}, { $set: {"yourFieldName": yourValue} }, false, true); Sample Data To understand the above syntax, let us create a collection with some documents. The query to create a collection with documents is as follows ? db.addNewFieldToEveryDocument.insertMany([ {"StudentName": "John", "StudentAddress": "US"}, {"StudentName": "David", "StudentAddress": "UK"}, {"StudentName": "Carol", "StudentAddress": "UK"}, {"StudentName": "Bob", "StudentAddress": "US"} ]); ...
Read MoreHow to remove a field completely from a MongoDB document?
You can use the $unset operator to remove a field completely from a MongoDB document. The syntax is as follows ? Syntax db.yourCollectionName.update({}, {$unset: {yourFieldName:1}}, false, true); Sample Data To understand the above syntax, let us create a collection with some documents. The query to create a collection with documents is as follows ? db.removeFieldCompletlyDemo.insertOne({"StudentName":"Larry", "StudentFavouriteSubject": ["Java", "C", "C++", "Python"]}); db.removeFieldCompletlyDemo.insertOne({"StudentName":"Mike", "StudentFavouriteSubject": ["Javascript", "HTML5", "CSS3"]}); db.removeFieldCompletlyDemo.insertOne({"StudentName":"Sam", "StudentFavouriteSubject": ["MongoDB", "MySQL", "SQL Server"]}); { "acknowledged" : true, "insertedId" : ObjectId("5c6ef55a6fd07954a48906a3") } ...
Read MoreConverting string to date in MongoDB?
To convert the string to date in MongoDB, use the $dateFromString operator within an aggregation pipeline. This operator parses a string and converts it to a proper date object. Syntax db.yourCollectionName.aggregate([ { $project: { anyVariableName: { $dateFromString: { ...
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