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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to get tag count in MongoDB query results based on list of names?
To get tag count in MongoDB query results based on a list of names, use the $in operator to match documents containing any of the specified names in an array field, then apply count() to get the total number of matching documents. Syntax db.collection.find({"arrayField": {$in: ["value1", "value2"]}}).count(); Sample Data db.tagCountDemo.insertMany([ {"ListOfNames": ["John", "Sam", "Carol"]}, {"ListOfNames": ["Bob", "David", "John"]}, {"ListOfNames": ["Mike", "Robert", "Chris"]}, {"ListOfNames": ["James", "Carol", "Jace"]} ]); { "acknowledged": true, ...
Read MoreGet documents expired before today in MongoDB?
To get documents expired before today in MongoDB, use the $lte operator with new Date() to find all documents where the date field is less than or equal to the current date. Syntax db.collection.find({ "dateField": { $lte: new Date() } }); Sample Data db.getDocumentsExpiredDemo.insertMany([ { "ArrivalDate": new ISODate("2019-05-11") }, { "ArrivalDate": new ISODate("2019-01-01") }, { "ArrivalDate": new ISODate("2019-05-10") }, { "ArrivalDate": new ISODate("2019-02-01") } ]); { "acknowledged": true, ...
Read MoreUpdate array in MongoDB document by variable index?
To update array in MongoDB document by variable index, use a JavaScript variable to dynamically construct the field path. This allows you to target specific array positions using a variable instead of hardcoding the index value. Syntax var indexVariable = yourIndexValue, updateObject = { "$set": {} }; updateObject["$set"]["arrayFieldName." + indexVariable] = "newValue"; db.collectionName.update({ "_id": ObjectId("...") }, updateObject); Sample Data Let us first create a collection with documents ? db.updateByVariableDemo.insertOne({ "StudentSubjects": ["MySQL", "Java", "SQL Server", "PL/SQL"] }); { ...
Read MoreDelete partial data in MongoDB?
To delete partial data in MongoDB, you can combine find(), skip(), and map() methods to select specific documents, then use remove() with the $in operator to delete them based on their IDs. Syntax var ids = db.collection.find({}, {_id: 1}).skip(N).toArray().map(function(doc) { return doc._id; }); db.collection.remove({_id: {$in: ids}}); Sample Data db.deleteDemo.insertMany([ {"Name": "John"}, {"Name": "Carol"}, {"Name": "Sam"}, {"Name": "David"}, {"Name": "Robert"}, {"Name": "Chris"}, ...
Read MoreSelecting only a single field from MongoDB?
To select only a single field from MongoDB, use the projection parameter in the find() method. Set the desired field to 1 to include it, and set _id to 0 to exclude the default ID field. Syntax db.collection.find( { query }, { fieldName: 1, _id: 0 } ); Sample Data db.selectingASingleFieldDemo.insertMany([ {"StudentFirstName": "John", "StudentAge": 23, "StudentCountryName": "US"}, {"StudentFirstName": "Carol", "StudentAge": 21, "StudentCountryName": "UK"}, {"StudentFirstName": "David", "StudentAge": 24, "StudentCountryName": "AUS"}, ...
Read MoreMongoDB divide aggregation operator?
The $divide operator in MongoDB performs division between two numbers during aggregation. It takes an array of exactly two numeric expressions and returns the result of dividing the first by the second. Syntax { $divide: [ , ] } Sample Data Let us first create a collection with documents ? db.aggregationOperatorDemo.insertOne({ "FirstValue": 392883, "SecondValue": 10000000000 }); { "acknowledged": true, "insertedId": ObjectId("5cd541452cba06f46efe9f01") } Following is the query to display all documents ...
Read MoreSearch an array of hashes in MongoDB?
To search an array of hashes in MongoDB, use dot notation to access fields within the hash objects stored in the array. This allows you to query specific key-value pairs within nested hash structures. Syntax db.collection.find({ "arrayName.fieldName": "value" }) Sample Data db.searchAnArrayDemo.insertMany([ { _id: 1, "TechnicalDetails": [{ "Language": "MongoDB" }] }, { _id: 2, "TechnicalDetails": [{ "Language": "MySQL" }] }, { _id: 3, "TechnicalDetails": [{ "Language": "MongoDB" }] }, { _id: 4, "TechnicalDetails": [{ "Language": "MongoDB" }] ...
Read MoreWant to update inner field in a MongoDB
To update an inner field in MongoDB, use the $set operator with dot notation to target the nested field within a document. This allows you to modify specific fields inside embedded documents without affecting other fields. Syntax db.collectionName.update( {"_id": ObjectId}, {$set: {"outerField.innerField": newValue}} ); Sample Data Let us create a collection with a document containing nested fields ? db.updateDocumentDemo.insertOne({ "StudentDetails": { "StudentFirstName": "Adam", "StudentLastName": ...
Read MoreQuery Array for 'true' value at index n in MongoDB?
To query an array for a true value at a specific index in MongoDB, use dot notation with the array field name followed by the index position. This allows you to check boolean values at exact array positions. Syntax db.collection.find({"arrayField.INDEX": true}); // Multiple index conditions db.collection.find({ $and: [ {"arrayField.INDEX1": true}, {"arrayField.INDEX2": true} ] }); Sample Data db.containsTrueValueDemo.insertOne({ "IsMarried": [true, false, true, true, true, true, ...
Read MoreHow to find MongoDB documents in a collection with a filter on multiple combined fields?
To find MongoDB documents with filters on multiple combined fields, use the $or or $and operators within the find() method. These operators allow you to combine multiple conditions across different fields. Syntax // OR operator - matches documents that satisfy ANY condition db.collection.find({ $or: [ { "field1": condition1 }, { "field2": condition2 } ] }); // AND operator - matches documents that satisfy ALL conditions db.collection.find({ ...
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