Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Articles on Trending Technologies
Technical articles with clear explanations and examples
What should be used to implement MySQL LIKE statement in MongoDB?
To implement MySQL LIKE statement functionality in MongoDB, use the $regex operator. This provides pattern matching capabilities similar to SQL's LIKE operator for text searches. Syntax db.collection.find({ "fieldName": { $regex: "pattern" } }); // Alternative syntax db.collection.find({ "fieldName": /pattern/ }); Sample Data db.likeInMongoDBDemo.insertMany([ { "Name": "Sam" }, { "Name": "John" }, { "Name": "Scott" }, { "Name": "Sean" }, { "Name": "Samuel" } ]); { ...
Read MoreMerge two array fields in MongoDB?
To merge two array fields in MongoDB, use the $setUnion operator in an aggregation pipeline. This operator combines arrays and automatically removes duplicates while preserving unique values from both arrays. Syntax db.collection.aggregate([ { $project: { "MergedFieldName": { $setUnion: ["$arrayField1", "$arrayField2"] } ...
Read MoreFind the count of users who logged in between specific dates with MongoDB
To find the count of users who logged in between specific dates in MongoDB, use the count() method with $gte and $lt operators to define the date range filter. Syntax db.collection.count({ "dateField": { "$gte": new Date("start-date"), "$lt": new Date("end-date") } }); Sample Data db.findDataByDateDemo.insertMany([ { "UserName": "John", "UserLoginDate": new ISODate("2019-01-31") }, { "UserName": "Larry", "UserLoginDate": new ISODate("2019-02-01") }, ...
Read MoreCalculate the average value in a MongoDB document grouping by null?
To calculate the average value across all documents in a MongoDB collection, use the $group operator with _id: null to group all documents together, then apply the $avg accumulator operator. Syntax db.collectionName.aggregate([ { $group: { _id: null, "averageFieldName": { $avg: "$fieldName" } } } ]); Sample Data ...
Read MoreImplement MongoDB $concatArrays even when some of the values are null?
Use the $ifNull operator with $concatArrays in the aggregation framework to concatenate arrays even when some fields are null or missing. The $ifNull operator replaces null values with an empty array, allowing concatenation to proceed successfully. Syntax db.collection.aggregate([ { $project: { concatenatedField: { $concatArrays: [ { $ifNull: ["$array1", []] }, { $ifNull: ["$array2", []] } ...
Read MoreMongoDB query check if value in array property?
To check if a value exists in an array property in MongoDB, you can use the $in operator for exact matches. This operator searches for documents where the array field contains any of the specified values. Syntax db.collection.find({ "arrayField": { $in: ["value1", "value2"] } }); Sample Data Let's create a collection with sample documents ? db.valueInArrayDemo.insertMany([ { "UserName": "John", "UserMessage": ["Hi", "Hello", "Bye"] }, ...
Read MoreHow do I push elements to an existing array in MongoDB?
To push elements to an existing array in MongoDB, use the $addToSet or $push operators with the update() method. The $addToSet adds elements only if they don't already exist, while $push always adds elements regardless of duplicates. Syntax // Using $addToSet (prevents duplicates) db.collection.update( {query}, { $addToSet: { "arrayField": "newElement" } } ); // Using $push (allows duplicates) db.collection.update( {query}, { $push: { "arrayField": "newElement" } } ); Sample Data Let us create a collection with a ...
Read MoreHow to print document value in MongoDB shell?
To print specific document values in MongoDB shell, use the forEach() method combined with the print() function. This allows you to extract and display individual field values from query results. Syntax db.collection.find(query, projection).forEach(function(document) { print(document.fieldName); }); Sample Data db.printDocumentValueDemo.insertMany([ {"InstructorName": "John Smith"}, {"InstructorName": "Sam Williams"}, {"InstructorName": "David Miller"} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5cd6804f7924bb85b3f48950"), ...
Read MoreHow to remove white spaces (leading and trailing) from string value in MongoDB?
To remove white spaces (leading and trailing) from string values in MongoDB, you can use the forEach() method combined with JavaScript's trim() function to iterate through documents and update them. Syntax db.collection.find().forEach(function(doc) { doc.fieldName = doc.fieldName.trim(); db.collection.update( { "_id": doc._id }, { "$set": { "fieldName": doc.fieldName } } ); }); Sample Data Let us first create a collection with documents containing white spaces ? ...
Read MoreHow to add a field with static value to MongoDB find query?
To add a field with static value to MongoDB find query, use the $literal operator with the aggregation framework. The $literal operator returns a value without parsing, making it perfect for adding constant values to query results. Syntax db.collection.aggregate([ { $project: { field1: 1, field2: 1, "staticFieldName": { $literal: ...
Read More