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
Finding a MongoDB document through a word
To find a MongoDB document through a word, use the find() method with regular expression pattern matching. The /word/i syntax performs case-insensitive search for the specified word within field values. Syntax db.collection.find({ "fieldName": /searchWord/i }); Create Sample Data db.demo212.insertMany([ {"details": [{"Name": "John Doe"}]}, {"details": [{"Name": "Chris Brown"}]}, {"details": [{"Name": "Robert doe"}]} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e3e2c7603d395bdc21346ff"), ...
Read MoreHow do you test if two external values are equal in a MongoDB criteria object?
To test if two external values are equal in a MongoDB criteria object, you can use the $type operator combined with a JavaScript expression that evaluates the equality condition and returns different BSON type numbers. Syntax db.collection.find({ field: "value", field: { $type: baseNumber + (value1 === value2) } }); Sample Data db.demo211.insertMany([ { id: 101, "Name": "Chris" }, { id: 102, "Name": null } ]); { "acknowledged": true, ...
Read MoreGet the count of a specific value in MongoDB
To get the count of a specific value in MongoDB, use the aggregate() method with $unwind and $group stages to count occurrences of array elements or use $size with $filter for a more efficient approach. Syntax db.collection.aggregate([ { $unwind: "$arrayField" }, { $match: { "arrayField.field": "targetValue" } }, { $group: { _id: "$_id", count: { $sum: 1 } } } ]); Sample Data db.demo210.insertOne({ details: [ { ClientName: "Robert" ...
Read MoreMongoDB query to convert the field value and create datetime day of month during projection?
To convert a field value and create datetime day of month during projection in MongoDB, use aggregate() with $unwind to flatten arrays and $dayOfMonth to extract the day from converted timestamps. Syntax db.collection.aggregate([ { "$unwind": "$arrayField" }, { "$project": { "fieldName": 1, "DayOfMonth": { ...
Read MoreSpecify a return format for data in MongoDB
In MongoDB, you can specify a custom return format for your data using aggregation operators like $addToSet. This operator collects unique values from multiple documents and returns them as an array, eliminating duplicates. Syntax db.collection.aggregate([ { "$group": { "_id": null, "fieldName": { "$addToSet": "$sourceField" } } }, ...
Read MoreMongoDB query to determine if a specific value does not exist?
To determine if a specific value does not exist, use the $ne (not equal) operator in MongoDB. This operator matches documents where the field value does not equal the specified value. Syntax db.collection.find({ "field": { "$ne": "value" } }) Sample Data db.demo206.insertMany([ { "ClientDetails": [ { "Name": "Chris", ...
Read MoreMongoDB query to count records on the basis of matching criteria
To count records on the basis of matching criteria in MongoDB, use the countDocuments() method with a query filter. This method returns the number of documents that match the specified criteria. Syntax db.collection.countDocuments({field1: value1, field2: value2}) Sample Data Let us create a collection with documents ? db.demo205.insertMany([ { "id": "101", "Name": "", "Age": "", "isActive": false ...
Read MoreDisplay only an element found in an array in MongoDB?
To display only an element found in an array in MongoDB, use aggregate() with $match, $unwind, and $project stages to filter and extract specific array elements. Syntax db.collection.aggregate([ { "$match": { "arrayField.searchField": "searchValue" }}, { "$unwind": "$arrayField" }, { "$match": { "arrayField.searchField": "searchValue" }}, { "$project": { "fieldToDisplay": "$arrayField.fieldName", "_id": 0 }} ]); Sample Data db.demo204.insertOne({ "_id": 101, "Name": "Chris", "Age": 23, ...
Read MoreQuery nested array by more than one condition in MongoDB
To query nested array by more than one condition in MongoDB, use the $elemMatch operator. This operator matches documents that contain an array field with at least one element that satisfies all the specified query conditions. Syntax db.collection.find({ "arrayField": { $elemMatch: { "field1": "value1", "field2": "value2" } } ...
Read MoreDisplay MongoDB explain query plan?
To analyze MongoDB query performance and execution strategy, use the explain() method. This provides detailed information about how MongoDB processes your queries, including execution stages, index usage, and performance metrics. Syntax db.collection.find(query).explain(); db.collection.find(query).explain("executionStats"); db.collection.find(query).explain("allPlansExecution"); Sample Data db.demo202.insertMany([ {"StudentFirstName": "Chris", "StudentAge": 21}, {"StudentFirstName": "David", "StudentAge": 23}, {"StudentFirstName": "Bob", "StudentAge": 22} ]); { "acknowledged": true, "insertedIds": [ ObjectId("5e3c3bd103d395bdc21346e8"), ...
Read More