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To find documents in MongoDB where at least one item from an array is not in another specified set, use the $nin operator or regex patterns to match arrays containing elements outside your target list. Syntax // Using $nin operator db.collection.find({ "arrayField": { $nin: ["value1", "value2"] } }); // Using regex for negative lookahead db.collection.find({ "arrayField": /^(?!value1|value2)/ }); Sample Data db.demo228.insertMany([ { "Subjects": ["MongoDB", "Java"] }, { "Subjects": ["MongoDB", "Java", "MySQL"] }, { "Subjects": ["Python", "JavaScript"] } ]); ... Read More
To update multiple documents from a list of key-value pairs in MongoDB, use bulk operations with initializeUnorderedBulkOp() to efficiently process multiple updates in a single operation. Syntax var bulkUpdateValue = [{"_id": "key1", "field": "value1"}, {"_id": "key2", "field": "value2"}]; var bulkUpdate = db.collection.initializeUnorderedBulkOp(); for (var i = 0; i < bulkUpdateValue.length; i++){ var updateItem = bulkUpdateValue[i]; bulkUpdate.find({_id: updateItem._id}).update({$set: {field: updateItem.field}}); } bulkUpdate.execute(); Sample Data db.demo227.insertMany([ {"_id": "101", "Name": "Chris"}, {"_id": "102", "Name": "Bob"} ]); { ... Read More
To exclude the _id field from MongoDB query results, use the $project operator in an aggregation pipeline. The $project stage allows you to include or exclude fields, suppress the _id field, and rename existing fields. Syntax db.collection.aggregate([ { $project: { _id: 0, field1: 1, field2: 1 } } ]); Sample Data db.demo226.insertMany([ { "Name": "Chris", "Age": 21 }, { "Name": "Bob", "Age": 20 }, { "Name": "David", "Age": 22 } ]); { ... Read More
To compare multiple properties in MongoDB, you can use the $where operator or the $expr operator. The $where allows JavaScript expressions to compare fields, while $expr uses aggregation expressions for better performance. Syntax // Using $where (JavaScript expression) db.collection.find({ $where: "this.field1 > this.field2" }); // Using $expr (Aggregation expression - Recommended) db.collection.find({ $expr: { $gt: ["$field1", "$field2"] } }); Sample Data db.demo223.insertMany([ {"Scores": [56, 78]}, {"Scores": [88, 45]}, {"Scores": [98, 79]} ]); { ... Read More
To add new array element in a MongoDB document, use the $ positional operator along with $set in an update operation. This allows you to add a new field to a specific element within an array. Syntax db.collection.update( {"arrayField.existingField": "matchValue"}, {"$set": {"arrayField.$.newField": "newValue"}} ); Sample Data db.demo222.insertOne({ "details": [ { "StudentName": "Chris", ... Read More
To fetch records with a specific case-sensitive name using MongoDB regular expressions, use the exact pattern match syntax /searchWord/. By default, MongoDB regex is case-sensitive, so /John/ will match "John" but not "john". Syntax db.collection.find({"field": /exactPattern/}); Sample Data db.demo221.insertMany([ {"Details": {"StudentName": "Chris", "StudentAge": 21}}, {"Details": {"StudentName": "John", "StudentAge": 20}}, {"Details": {"StudentName": "Bob", "StudentAge": 22}}, {"Details": {"StudentName": "john", "StudentAge": 24}} ]); { "acknowledged": true, "insertedIds": [ ... Read More
To get all embedded documents with specific fields in MongoDB, use the $project aggregation operator. This allows you to extract and display specific fields from embedded documents. Syntax db.collection.aggregate([ { $project: { "fieldName": "$embeddedDocument.fieldName", "anotherField": "$embeddedDocument.anotherField" } } ]); Sample Data db.demo220.insertMany([ ... Read More
To search for a specific domain name from URL records in MongoDB, use the regex pattern with the /i flag for case-insensitive matching. This allows you to find URLs containing specific domain names regardless of their capitalization. Syntax db.collection.find({ "fieldName": /domainName/i }); Sample Data Let us create a collection with URL documents − db.demo219.insertMany([ {"details": {"WebsiteURL": "www.EXAMPLE.com"}}, {"details": {"WebsiteURL": "www.gmail.com"}}, {"details": {"WebsiteURL": "www.example.com"}} ]); { "acknowledged": true, ... Read More
The MongoDB aggregation pipeline processes documents through multiple stages, where each stage transforms the documents as they pass through the pipeline. It's a powerful framework for data analysis and transformation operations. Syntax db.collection.aggregate([ { $stage1: { /* stage operations */ } }, { $stage2: { /* stage operations */ } }, { $stageN: { /* stage operations */ } } ]) Sample Data db.demo218.insertMany([ {"Name": "Chris", "Branch": "CS", "Marks": [65, 78, 36, 90]}, ... Read More
To trim spaces from field in MongoDB, use the $trim operator within an aggregation pipeline. The $trim operator removes whitespace characters from the beginning and end of a string. Syntax db.collection.aggregate([ { $project: { fieldName: { $trim: { input: "$sourceField" } } }} ]) Sample Data db.demo217.insertMany([ {"FullName": " Chris Brown"}, {"FullName": " David Miller"}, {"FullName": " John Doe"} ]); { ... Read More