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 by AmitDiwan
Page 548 of 840
Check for duplicates in an array in MongoDB?
To check for duplicates in an array in MongoDB, use the $unwind and $group operators within an aggregation pipeline to identify array elements that appear more than once in the same document. Syntax db.collection.aggregate([ { $project: { arrayField: 1 } }, { $unwind: "$arrayField" }, { $group: { _id: { _id: "$_id", value: "$arrayField" }, count: { $sum: 1 } } }, { $match: { count: { $gt: 1 } } }, { $group: { _id: "$_id._id", ...
Read MoreSort MongoDB field which contains both integer and decimal values?
To sort a MongoDB field containing both integer and decimal values, use the sort() method. MongoDB automatically handles mixed numeric types (integers and decimals) in the same field and sorts them by their numeric value. Syntax db.collection.find().sort({fieldName: 1}); // 1 for ascending, -1 for descending Sample Data db.demo755.insertMany([ {"Value": 10}, {"Value": 10.5}, {"Value": 9.5}, {"Value": 12.5}, {"Value": 11.5}, {"Value": 6} ]); { ...
Read MoreHow to convert birth date records to age with MongoDB
To convert birth date records to age in MongoDB, use the $dateDiff operator or calculate the difference between the current date and birth date using $subtract and $divide operators in an aggregation pipeline. Syntax db.collection.aggregate([ { $project: { age: { $divide: [ ...
Read MoreFilter specific values from a MongoDB document
To filter specific values from a MongoDB document, use the $filter operator in aggregation pipelines. This operator allows you to select array elements that match specific conditions and return only those elements. Syntax { $filter: { input: "$arrayField", as: "variable", cond: { condition } } } Sample Data db.demo751.insertOne({ _id: 101, details: [ ...
Read MoreHow to get max values for distinct elements in MongoDB
To get max values for distinct elements in MongoDB, use the $group operator with $max to find the highest value for each distinct element. This aggregation pipeline groups documents by a field and returns the maximum value within each group. Syntax db.collection.aggregate([ { $group: { _id: "$fieldName", maxValue: { $max: "$valueField" } } ...
Read MoreMongoDB query to update each field of documents in collection with a formula?
To update each field of documents in collection with a formula in MongoDB, use the $mul operator with the positional all operator $[] to apply mathematical operations across all array elements. Syntax db.collection.update( {}, { $mul: { "arrayField.$[].fieldName": formulaValue } }, { multi: true } ); Sample Data db.demo749.insertOne({ "details": [ {"id": 1, "a": 10}, {"id": 2, "a": 5}, ...
Read MoreWhat is the maximum size of a document in MongoDB?
The maximum size of a document in MongoDB is 16 MB (16, 777, 216 bytes). This limit ensures efficient memory usage and prevents documents from consuming excessive resources during operations. Syntax // Document structure with size limit { field1: "value1", field2: "value2", // ... additional fields // Total document size ≤ 16 MB } Sample Data Let us create a collection with sample documents ? db.demo748.insertMany([ {_id: 101, Name: "Chris", Age: 21}, ...
Read MorePushing values into array with multi field set to TRUE?
To push values into arrays across multiple documents in MongoDB, use the $push operator with update() and set the multi field to true. This allows updating all matching documents in a single operation. Syntax db.collection.update( {filter}, { $push: { arrayField: "value" } }, { multi: true } ); Sample Data db.demo747.insertMany([ { "CountryName": ["US", "IND"] }, { "CountryName": ["UK", "US"] }, { "CountryName": ["UK", "IND"] } ]); ...
Read MoreFind posts that are older than current date in MongoDB?
To find posts older than current date in MongoDB, use the $lte operator with new Date() to compare document dates against the current system date. Syntax db.collection.find({ dateField: { $lte: new Date() } }); Sample Data Let us create a collection with documents containing different due dates ? db.demo746.insertMany([ { DueDate: new Date("2020-01-10") }, { DueDate: new Date("2020-10-10") }, { DueDate: new Date("2020-03-05") }, { DueDate: new Date("2020-05-04") } ]); ...
Read MoreConcatenate with condition in MongoDB?
To concatenate with condition in MongoDB, use $cond with $concat in an aggregation pipeline. This allows you to perform string concatenation based on specific conditions and filter results accordingly. Syntax db.collection.aggregate([ { "$redact": { "$cond": [ { "$eq": [{ "$concat": ["$field1", "$field2"] }, "targetValue"] }, ...
Read More