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 596 of 840
How to query with nand operator in MongoDB?
MongoDB doesn't have a $nand operator, but you can achieve NAND (Not AND) logic by using $or with $ne operators. This returns documents where at least one condition is false. Syntax db.collection.find({ $or: [ { "field1": { $ne: value1 } }, { "field2": { $ne: value2 } } ] }); Sample Data db.demo266.insertMany([ { "active1": true, "active2": false }, { "active1": ...
Read MoreMongoDB query to update only certain fields?
To update only certain fields in MongoDB, use the $set operator. This operator modifies specific fields without affecting other existing fields in the document. Syntax db.collection.update( { "field": "value" }, { $set: { "fieldToUpdate": "newValue" } } ); Sample Data Let us create a collection with sample documents − db.demo265.insertMany([ {"id": 101, "Name": "Chris"}, {"id": 102, "Name": "Bob"}, {"id": 103, "Name": "David"} ]); { "acknowledged": ...
Read MoreUsing count equivalent in MongoDB to find top users with max occurrence
To find the top users with maximum occurrence in MongoDB, use the $group stage with aggregate() to count occurrences, then $sort and $limit to get the top results. Syntax db.collection.aggregate([ { $group: { _id: "$fieldName", count: { $sum: 1 } } }, { $sort: { count: -1 } }, { $limit: numberOfTopResults } ]); Sample Data Let us create a collection with user documents ? db.demo264.insertMany([ { "Name": "Chris" }, { "Name": ...
Read MoreMongoDB query to skip documents
To skip documents in MongoDB, use the skip() method. This method allows you to skip a specified number of documents from the beginning of the result set, useful for pagination and result navigation. Syntax db.collection.find().skip(number) Sample Data db.demo263.insertMany([ {_id: 100}, {_id: 200}, {_id: 300} ]); { "acknowledged": true, "insertedIds": { "0": 100, "1": 200, "2": 300 } } ...
Read MoreInvert Result of MongoDB Query (Implement Opposite of $and operation)?
To invert the result of a MongoDB query (opposite of $and operation), use $or combined with $ne operators. This applies De Morgan's Law: NOT (A AND B) = (NOT A) OR (NOT B). Syntax db.collection.find({ $or: [ { "field1": { $ne: "value1" } }, { "field2": { $ne: "value2" } } ] }); Sample Data db.demo4.insertMany([ { uid: 1, "Name": "Chris", "Age": 22 }, ...
Read MoreModify sequence in MongoDB
To modify a sequence in MongoDB, use findAndModify() method to atomically increment a counter value. This approach creates auto-incrementing sequence numbers for document IDs. Syntax db.collection.findAndModify({ query: {_id: "sequenceName"}, update: {$inc: {sequence_value: 1}}, new: true }); Create Sample Data First, create a collection with an initial document ? db.demo261.insertOne({_id:100, Name:"Chris"}); { "acknowledged" : true, "insertedId" : 100 } db.demo261.find(); { "_id" : 100, "Name" : "Chris" } Example: Create ...
Read MoreGet MongoDB documents that contains specific attributes in array
To get MongoDB documents that contain specific attributes in an array, use $and along with dot notation to match multiple field values within the same array field. Syntax db.collection.find({ $and: [ {"arrayField.attribute1": "value1"}, {"arrayField.attribute2": "value2"} ] }); Sample Data Let us first create a collection with documents − db.demo2.insertMany([ { "StudentInformation": [ ...
Read MoreHow to run MongoDB shell using mongos command?
The mongos command is used to start a MongoDB router process in sharded cluster deployments. It acts as an interface between client applications and the sharded cluster, routing queries to the appropriate shards. Syntax mongos --configdb /, Basic mongos Command To start the mongos router, specify the configuration replica set ? mongos --configdb configReplSet/config1.example.com:27019, config2.example.com:27019, config3.example.com:27019 Common mongos Options Here are the most frequently used mongos command options ? mongos --configdb configReplSet/config1:27019, config2:27019 --port 27017 mongos --configdb configReplSet/config1:27019, config2:27019 --logpath /var/log/mongodb/mongos.log mongos --configdb configReplSet/config1:27019, config2:27019 --fork --logpath ...
Read MoreHow to update % printed to Console from MongoDB?
To update and print percentage values to console from MongoDB script, create a variable with your numeric value and use the print() method with toFixed() to format decimal places. Syntax var variableName = numericValue; print(variableName.toFixed(decimalPlaces) + " %"); Example Create a variable with a percentage value and format it to 2 decimal places ? var amount = 10.58945; print(amount.toFixed(2) + " %"); The output of the above code is ? 10.59 % Key Points Use toFixed() to control the number of decimal places displayed. ...
Read MoreInvoke convertToCapped and convert an existing collection to capped in MongoDB
To convert an existing collection to capped in MongoDB, use the convertToCapped command with runCommand(). A capped collection has a fixed size and automatically removes old documents when the size limit is reached. Syntax db.runCommand({ convertToCapped: "collectionName", size: sizeInBytes }); Sample Data Let us create a regular collection with some documents ? db.demo260.insertMany([ {"Name": "Chris"}, {"Name": "Bob"}, {"Name": "David"} ]); { "acknowledged": true, ...
Read More