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Articles on Trending Technologies
Technical articles with clear explanations and examples
Adding new property to each document in a large MongoDB collection?
To add a new property to each document in a large MongoDB collection, use the forEach() method combined with update() and $set operator. This approach iterates through all documents and adds the new field dynamically. Syntax db.collection.find().forEach(function(doc) { db.collection.update( {_id: doc._id}, {$set: {newProperty: computedValue}} ); }); Create Sample Data db.addingNewPropertyDemo.insertMany([ {"StudentName": "John", "StudentAge": 23, "CountryName": "US"}, {"StudentName": "David", "StudentAge": 21, "CountryName": ...
Read MoreHow to terminate a MongoDB shell script earlier?
To terminate a MongoDB shell script earlier, you can use the quit() or quit(1) command. This immediately exits the MongoDB shell and returns control to the operating system command prompt. Syntax quit() quit(1) Where quit() exits with status code 0 (success), and quit(1) exits with status code 1 (error). Sample Data Let us first create a collection with sample documents to demonstrate the quit functionality ? db.flightInformation.insertMany([ {"FlightName": "Flight-1", "ArrivalTime": new ISODate("2019-03-12")}, {"FlightName": "Flight-2", "ArrivalTime": new ISODate("2019-03-31")} ]); { ...
Read MoreRenaming column name in a MongoDB collection?
To rename a field (column) name in a MongoDB collection, use the $rename operator. This operator allows you to change field names across multiple documents in a single operation. Syntax db.collectionName.updateMany( {}, { $rename: { "oldFieldName": "newFieldName" } } ); Sample Data Let us create a collection with sample documents ? db.renamingColumnNameDemo.insertMany([ { "StudentName": "Larry", "Age": 23 }, { "StudentName": "Sam", "Age": 26 }, { "StudentName": "Robert", "Age": 27 } ]); ...
Read MoreHow to store query result (a single document) into a variable?
To store a query result (a single document) into a variable in MongoDB, use the var keyword with find().limit(1) to retrieve only one document. You can then access the stored result by referencing the variable name. Syntax var variableName = db.collectionName.find().limit(1); variableName; // Display the stored result Sample Data Let us first create a collection with sample documents ? db.storeQueryResultDemo.insertMany([ {"ClientName": "Chris", "ClientAge": 23}, {"ClientName": "Robert", "ClientAge": 21}, {"ClientName": "Sam", "ClientAge": 25}, {"ClientName": "Mike", "ClientAge": 26} ...
Read MoreHow to find two random documents in a MongoDB collection of 6?
To find two random documents from a MongoDB collection, use the $sample aggregation stage. This operator randomly selects a specified number of documents from the collection efficiently. Syntax db.collection.aggregate([ { $sample: { size: NumberOfDocuments } } ]); Sample Data Let us create a collection with 6 student documents ? db.twoRandomDocumentDemo.insertMany([ {"StudentId": 10}, {"StudentId": 100}, {"StudentId": 45}, {"StudentId": 55}, {"StudentId": 5}, {"StudentId": 7} ]); ...
Read MoreHow to check if field is a number in MongoDB?
To check if a field is a number in MongoDB, use the $type operator with the value "number". This operator matches documents where the specified field contains numeric values (integers, doubles, or decimals). Syntax db.collectionName.find({fieldName: {$type: "number"}}); Sample Data Let us create a collection with documents containing different data types ? db.checkIfFieldIsNumberDemo.insertMany([ {"StudentName": "John", "StudentAge": 23}, {"StudentName": "Chris", "StudentMathScore": 98, "StudentCountryName": "US"}, {"StudentName": "Robert", "StudentCountryName": "AUS"}, {"StudentId": 101, "StudentName": "Larry", "StudentCountryName": "AUS"} ]); ...
Read MoreBuilding Multiple Indexes at once in MongoDB?
To build multiple indexes at once in MongoDB, use the createIndexes() method and pass multiple index specifications in an array. This approach is more efficient than creating indexes one by one. Syntax db.collection.createIndexes([ { "field1": 1 }, { "field2": -1 }, { "field3": 1, "field4": 1 } ]); Example Let's create multiple single-field indexes on a collection ? db.multipleIndexesDemo.createIndexes([ {"First": 1}, {"Second": 1}, {"Third": 1}, ...
Read MoreHow to get documents by tags in MongoDB?
To find documents by tags in MongoDB, you can use the $elemMatch operator or simple array matching. MongoDB provides several ways to query documents containing specific tags in array fields. Syntax // Using $elemMatch operator db.collection.find({Tags: { $elemMatch: { $eq: "tagValue" } }}); // Simple array matching db.collection.find({Tags: "tagValue"}); // Multiple tags using $in db.collection.find({Tags: { $in: ["tag1", "tag2"] }}); Sample Data db.getDocumentsByTagsDemo.insertMany([ {"Tags": ["Tag-1", "Tag-2", "Tag-3"]}, {"Tags": ["Tag-2", "Tag-4", "Tag-5"]}, {"Tags": ["Tag-6", "Tag-4", "Tag-3"]} ]); ...
Read MoreHow to get connected clients in MongoDB?
To get connected clients in MongoDB, use the db.currentOp() method with true parameter to display all operations including idle connections. The client field in the output shows the IP address and port of each connected client. Syntax db.currentOp(true) Example Run the following command to view all connected clients ? db.currentOp(true) The output displays all connected clients with detailed information ? { "inprog" : [ { "host" : "DESKTOP-QN2RB3H:27017", ...
Read MoreHow do you limit an array sub-element in MongoDB?
You can use $slice operator to limit array elements in MongoDB query results. The $slice operator controls how many elements from an array field are returned in the projection. Syntax db.collection.find( {}, { "arrayField": { $slice: N } } ) Where N can be: Positive number: Returns first N elements Negative number: Returns last N elements [skip, limit]: Skips elements and limits result Sample Data db.limitAnArrayDemo.insertOne({ _id: 101, "PlayerName": "Bob", ...
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