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Articles by AmitDiwan
Page 552 of 840
Difference between NumberLong(x) and NumberLong("x") in MongoDB?
The NumberLong(x) function can lose precision with very large integers due to JavaScript's number limitations, while NumberLong("x") preserves exact precision by accepting the number as a string. Syntax NumberLong(number) // May lose precision for very large values NumberLong("string") // Preserves exact precision Example Let us create a collection with documents to demonstrate the difference ? db.demo603.insertMany([ {"longValue": NumberLong(988998985857575789)}, {"longValueInString": NumberLong("988998985857575789")} ]); { "acknowledged": true, "insertedIds": ...
Read MoreMongoDB aggregation of elements with similar ids in different documents?
To aggregate elements with similar ids in different documents, use $group in MongoDB aggregation pipeline. This technique groups documents by id and collects all related data into arrays. Syntax db.collection.aggregate([ { $group: { '_id': { id: "$id", "fieldName": "$fieldName" }, "count": { "$sum": 1 } }}, { $group: { '_id': "$_id.id", "aggregatedData": { ...
Read MoreUpdate in MongoDB and prevent overwrite?
To update a document in MongoDB without overwriting the entire document, use the $set operator to modify specific fields while preserving existing data. This prevents accidental data loss during updates. Syntax db.collection.update( { "field": "matchValue" }, { $set: { "fieldToUpdate": "newValue" } } ); Sample Data db.demo601.insertMany([ { id: 1, userDetails: { userName: ...
Read MoreCreate a new user and set role in MongoDB
To create a new user and set their role in MongoDB, use the createUser() method. The userAdminAnyDatabase role provides comprehensive administrative privileges across all databases. Syntax use admin db.createUser( { user: "yourUserName", pwd: "yourPassword", roles: [ { role: "yourRoleName", db: "yourDatabaseName" } ] } ) Example Create a user with the "userAdminAnyDatabase" role ? use admin db.createUser( ...
Read MoreHow to use custom variable while updating a MongoDB document?
To use custom variables while updating MongoDB documents, first declare a variable with var, then reference it in your update() operation. This allows for dynamic updates and better code reusability. Syntax var variableName = yourValue; db.collectionName.update( { filter }, { $set: { fieldName: variableName } } ); Create Sample Data db.demo600.insertMany([ { id: 1, Name: "Robert" }, { id: 2, Name: "Mike" }, { id: 3, Name: "Sam" } ]); ...
Read MoreHow to subtract values (TotalPrice – Discount) from document field values in MongoDB?
To subtract values from document field values in MongoDB, use the $subtract operator within the aggregation pipeline. This operator performs arithmetic subtraction between numeric field values or expressions. Syntax db.collection.aggregate([ { $project: { newField: { $subtract: ["$field1", "$field2"] } ...
Read MoreFind which MongoDB document contains a specific string?
To find which document contains a specific string, use $regex along with find(). The regex operator performs pattern matching to locate documents containing the specified text substring. Syntax db.collection.find({ fieldName: { $regex: /pattern/flags } }); Sample Data db.demo597.insertMany([ { "Name": "John Doe" }, { "Name": "John Smith" }, { "Name": "Chris Brown" }, { "Name": "Adam Smith" } ]); { "acknowledged": true, ...
Read MoreMongoDB query to update nested document
To update a nested document in MongoDB, use the $ positional operator with the $set operator. The $ operator identifies the array element that matches the query condition and allows you to update specific fields within that element. Syntax db.collection.update( {"arrayName.field": "matchValue"}, { $set: { "arrayName.$.field": "newValue" } } ); Create Sample Data Let us create a collection with documents − db.demo595.insertOne({ "Information": [ { "_id": new ObjectId(), "Name": "Chris" }, ...
Read MoreMongoDB query to limit the returning values of a field?
To limit the returning values of a field in MongoDB, use the $slice operator in the projection parameter of the find() method. This is particularly useful for limiting array elements returned in query results. Syntax db.collection.find( {}, { "arrayField": { "$slice": numberOfElements } } ); Sample Data db.demo594.insertOne({ id: 1, details: [ { Name: "Chris", Age: 21 }, { Name: "Bob", ...
Read MoreFetch specific multiple documents in MongoDB
To fetch specific multiple documents in MongoDB, use the $in operator to match documents where a field value equals any value in a specified array. Syntax db.collection.find({ "field": { $in: [value1, value2, value3, ...] } }); Sample Data Let us create a collection with documents − db.demo593.insertMany([ { id: 1, "Name": "Chris" }, { id: 2, "Name": "John" }, { id: 3, "Name": "Bob" }, { id: 4, "Name": "Sam" } ]); ...
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