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Articles on Trending Technologies
Technical articles with clear explanations and examples
MongoDB query to return only embedded document?
While MongoDB doesn't return only embedded documents directly, you can use projection to return specific fields and the $elemMatch operator to filter array elements that match certain conditions. Syntax db.collection.find( { "arrayField.nestedField": { $gte: value } }, { "arrayField": { $elemMatch: { "nestedField": { $gte: value } } } } ); Sample Data db.queryToEmbeddedDocument.insertOne({ "UserName": "Larry", "PostDetails": [ { "UserMessage": "Hello", "UserLikes": 8 }, ...
Read MoreSearch a string with special characters in a MongoDB document?
To search a string with special characters in MongoDB document, you can use backslash (\) to escape the special character in a regular expression. Here, we have special character $ in our string. Syntax db.collection.find({ "fieldName": /.*\specialCharacter.*/i }); Sample Data Let us first create a collection with documents ? db.searchDocumentWithSpecialCharactersDemo.insertMany([ { "UserId": "Smith$John123", "UserFirstName": "John", "UserLastName": "Smith" ...
Read MoreCan we use NOT and AND together in MongoDB?
Yes, we can use NOT and AND together in MongoDB. MongoDB doesn't have direct NOT and AND operators, but we achieve this using $or and $ne operators following De Morgan's law: NOT (X AND Y) = NOT X OR NOT Y. Syntax db.collection.find({ "$or": [ {"field1": {"$ne": "value1"}}, {"field2": {"$ne": "value2"}} ] }); Sample Data db.NotAndDemo.insertMany([ {"StudentName": "John", "StudentCountryName": "US"}, {"StudentName": ...
Read MoreHow to remove document on the basis of _id in MongoDB?
To remove a document based on its _id in MongoDB, use the remove() method with the ObjectId as the matching criteria. Each document has a unique _id field that serves as the primary key. Syntax db.collectionName.remove({"_id": ObjectId("yourObjectId")}); Sample Data Let us first create a collection with sample documents ? db.removeDocumentOnBasisOfId.insertMany([ {"UserName": "Larry", "UserAge": 23, "UserCountryName": "US"}, {"UserName": "Sam", "UserAge": 21, "UserCountryName": "UK"}, {"UserName": "Chris", "UserAge": 24, "UserCountryName": "US"}, {"UserName": "Robert", "UserAge": 26, "UserCountryName": "UK"}, ...
Read MoreIncrement a value in a MongoDB nested object?
To increment a value in a MongoDB nested object, use the $inc operator combined with the $ positional operator to target the specific nested element and increment its numeric value. Syntax db.collection.update( {"nestedArray.field": "matchValue"}, { $inc: { "nestedArray.$.fieldToIncrement": incrementValue } } ); Create Sample Data Let us create a collection with a document containing nested array objects ? db.incrementValueDemo.insertOne({ "StudentName": "Larry", "StudentCountryName": "US", "StudentDetails": [ ...
Read MoreInserting the current datetime in MongoDB?
To insert current datetime in MongoDB, use new Date() during insertion or $setOnInsert with upsert operations. MongoDB stores dates in ISODate format with UTC timezone. Syntax // Direct insertion db.collection.insertOne({ fieldName: new Date() }); // With upsert operation db.collection.update( { _id: value }, { $set: { field1: "value" }, $setOnInsert: { dateField: new Date() } }, { upsert: true } ); Sample Data db.addCurrentDateTimeDemo.insertMany([ { "StudentName": "John", "StudentAdmissionDate": new Date("2012-01-21") }, { ...
Read MoreHow to search document in MongoDB by _id
To search a document in MongoDB by _id, you need to use the ObjectId() function to wrap the _id value, since MongoDB stores document IDs as ObjectId objects. Syntax db.collectionName.find({"_id": ObjectId("your_object_id_here")}); Create Sample Data Let us create a collection with sample documents ? db.searchDocumentDemo.insertMany([ {"UserId": 1, "UserName": "Larry"}, {"UserId": 2, "UserName": "Mike"}, {"UserId": 3, "UserName": "David"}, {"UserId": 4, "UserName": "Chris"}, {"UserId": 5, "UserName": "Robert"}, {"UserId": 6, "UserName": "Sam"} ...
Read MoreHow to create double nested array in MongoDB?
To create a double nested array in MongoDB, use insertOne() or insertMany() with documents containing arrays of objects that themselves contain arrays. A double nested array means an array within an array structure. Syntax db.collection.insertOne({ "field1": "value1", "outerArray": [ { "innerField": "value", "innerArray": [ ...
Read MoreGet the array of _id in MongoDB?
In MongoDB, the _id field is a mandatory field that acts as the primary key for each document. To retrieve documents by matching their _id values against an array of specific values, use the $in operator. Syntax db.collectionName.find({ _id: { $in: [value1, value2, value3, ...] } }); Create Sample Data db.selectInWhereIdDemo.insertMany([ {"_id": 23}, {"_id": 28}, {"_id": 45}, {"_id": 75}, {"_id": 85}, {"_id": 145} ]); { ...
Read MoreGet all the column names in a table in MongoDB
In MongoDB, there is no concept of columns since MongoDB is schema-less and does not contain tables. It contains the concept of collections and a collection has different types of documents with varying field structures. Syntax // Insert documents with different field structures db.collectionName.insertOne({"fieldName1": "value1", "fieldName2": "value2"}); // Get all field names from a single document db.collectionName.findOne(); // Get all documents to see different field structures db.collectionName.find(); Sample Data Let us create a collection with documents having different field structures ? db.collectionOnDifferentDocumentDemo.insertMany([ {"UserName": "Larry"}, ...
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