For this, use $group in MongoDB. Within that, use $unwind, $group, $addToSet, etc. Let us create a collection with documents −> db.demo456.insertOne( ... { _id: 101, StudentName: ["Chris", "David"] } ... ); { "acknowledged" : true, "insertedId" : 101 } > > db.demo456.insertOne( ... { _id: 102, StudentName: ["Mike", "Sam"] } ... ); { "acknowledged" : true, "insertedId" : 102 } > db.demo456.insertOne( ... { _id: 103, StudentName: ["John", "Jace"] } ... ); { "acknowledged" : true, "insertedId" : 103 } > db.demo456.insertOne( ... { _id: 104, StudentName: ["Robert", "John"] } ... ); { "acknowledged" : true, "insertedId" : 104 ... Read More

To display a list of objects based on a specific property, use dot notation in find(). Let us create a collection with documents −> db.demo455.insertOne({"Information":{"Student":[{"Name":"Chris", "Age":22}]}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7e1876dbcb9adb296c95c5") } > db.demo455.insertOne({"Information":{"Student":[{"Name":"David", "Age":21}]}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7e1883dbcb9adb296c95c6") } > db.demo455.insertOne({"Information":{"Student":[{"Name":"Bob", "Age":24}]}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7e188adbcb9adb296c95c7") } > db.demo455.insertOne({"Information":{"Student":[{"Name":"Robert", "Age":21}]}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7e18bcdbcb9adb296c95c8") }Display all documents from a collection with the help of find() method −> db.demo455.find();This will produce the following output −{ "_id" : ObjectId("5e7e1876dbcb9adb296c95c5"), "Information" : { "Student" : [ { ... Read More

To publish the latest N records with sorting, use sort() along with limit(). Here, set the number of records you want to show with limit(). Let us create a collection with documents −> db.demo454.insertOne({"ClientName":"Chris"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7cce8cdbcb9adb296c95c0") } > db.demo454.insertOne({"ClientName":"John"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7cce95dbcb9adb296c95c1") } > db.demo454.insertOne({"ClientName":"Bob"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7cce9fdbcb9adb296c95c2") } > db.demo454.insertOne({"ClientName":"David"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7ccea6dbcb9adb296c95c3") } > db.demo454.insertOne({"ClientName":"Mike"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7cceafdbcb9adb296c95c4") }Display all documents from a collection with the help of find() method −> db.demo454.find();This ... Read More

To filter documents based on an array, use $elemMatch. The $elemMatch operator matches documents that contain an array field.Let us create a collection with documents −> db.demo453.insertOne( ... { _id: 101, details: [ { Name: "David", Marks: 60 }, { Name: "Mike", Marks: 55} ] } ... ) { "acknowledged" : true, "insertedId" : 101 } > db.demo453.insertOne( ... { _id: 102, details: [ { Name: "Bob", Marks: 80 }, { Name: "Sam", Marks: 78} ] } ... ) { "acknowledged" : true, "insertedId" : 102 } > db.demo453.insertOne( ... { _id: 103, details: [ { Name: "Carol", Marks: 67 ... Read More

To get the count of repeated values in different documents, use aggregate(). Let us create a collection with documents −> db.demo452.insertOne({"StudentName":"John", "StudentAge":21});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3371f552a0ebb0a6f3") } > db.demo452.insertOne({"StudentName":"John", "StudentAge":22});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3671f552a0ebb0a6f4") } > db.demo452.insertOne({"StudentName":"John", "StudentAge":23});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e3971f552a0ebb0a6f5") } > db.demo452.insertOne({"StudentName":"David", "StudentAge":24});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e4371f552a0ebb0a6f6") } > db.demo452.insertOne({"StudentName":"David", "StudentAge":25});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b7e4571f552a0ebb0a6f7") }Display all documents from a collection with the help of find() method −> db.demo452.find();This will produce the following output −{ "_id" : ... Read More

To get the mean daily average count of recorded documents, use aggregate(). Within that, use $project and $group.Let us create a collection with documents −Example> db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-15T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6e9") } > db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-14T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6ea") } > db.demo451.insertOne({ ... DueDate:new ISODate("2020-03-13T10:50:35.000Z"), ... Value: 10 ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b5c5d71f552a0ebb0a6eb") }Display all documents from a collection with the help of find() ... Read More

In order to reach subdata, you need to use key in MongoDB. Let us create a collection with documents −>db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"Chris", "StudentAge":21}}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7b590e71f552a0ebb0a6e6") } >db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"David", "StudentAge":23}}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b591a71f552a0ebb0a6e7") } >db.demo450.insertOne({"Information":{"StudentDetails":{"StudentName":"Mike", "StudentAge":22}}});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7b592271f552a0ebb0a6e8") }Display all documents from a collection with the help of find() method −> db.demo450.find();This will produce the following output −{ "_id" : ObjectId("5e7b590e71f552a0ebb0a6e6"), "Information" : { "StudentDetails" : { "StudentName" : "Chris", "StudentAge" : 21 } } } { "_id" : ObjectId("5e7b591a71f552a0ebb0a6e7"), "Information" : { "StudentDetails" : { ... Read More

To insert an item to an already created array inside an object, use MongoDB $push. Let us create a collection with documents −> db.demo449.insertOne( ... { ...    details1: { ...       details2: [{ ...          _id:new ObjectId(), ...             Name:"Chris" ...       }], ...       details3: [{ ...          _id:new ObjectId(), ...          Name:"David" ...       }] ...    } ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e7a40e971f552a0ebb0a6e3") }Display all documents from ... Read More

The findOneAndDelete() deletes single documents from the collection on the basis of a filter and sort criteria as well as it returns the deleted document.The deleteOne() removes single document from the collection.Let us see an example and create a collection with documents −> db.demo448.insertOne({"Name":"Chris", "Age":21});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a291cbbc41e36cc3caeca") } > db.demo448.insertOne({"Name":"David", "Age":23});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a2926bbc41e36cc3caecb") } > db.demo448.insertOne({"Name":"Bob", "Age":22});{    "acknowledged" : true,    "insertedId" : ObjectId("5e7a2930bbc41e36cc3caecc") }Display all documents from a collection with the help of find() method −> db.demo448.find();This will produce the following output −{ "_id" : ObjectId("5e7a291cbbc41e36cc3caeca"), ... Read More

For this, you can use $lookup. Let us create a collection with documents −> db.demo446.insert([ ...    { "ProductName": "Product1", "ProductPrice": 60 }, ...    { "ProductName": "Product2", "ProductPrice": 90 } ... ]) BulkWriteResult({    "writeErrors" : [ ],    "writeConcernErrors" : [ ],    "nInserted" : 2,    "nUpserted" : 0,    "nMatched" : 0,    "nModified" : 0,    "nRemoved" : 0,    "upserted" : [ ] })Display all documents from a collection with the help of find() method −> db.demo446.find();This will produce the following output −{ "_id" : ObjectId("5e790766bbc41e36cc3caec3"), "ProductName" : "Product1", "ProductPrice" : 60 } { ... Read More