To query on an array of objects for nested documents, use find(). Let us create a collection with documents −> db.demo763.insertOne( ...    { ...       _id:1, ...       CountryName:"US", ...       "studentInformation": [ ...          { ...             StudentName:"Chris", ...          }, ...          { ...             StudentName:"David", ...             StudentAge:22 ...          } ...       ] ...    } ... ); { "acknowledged" : true, "insertedId" : 1 }Display all documents from a collection with the help of find() method −> db.demo763.find();This will produce the following output −{ "_id" : 1, "CountryName" : "US", "studentInformation" : [ { "StudentName" : "Chris" }, { "StudentName" : "David", "StudentAge" : 22 } ] }Following is how to query an array of objects to fetch specific nested documents −> db.demo763.find({}, ... { ...    studentInformation: { ...       $elemMatch: { ...          StudentAge: { ...             $exists: true ...          } ...       } ...    } ... })This will produce the following output −{ "_id" : 1, "studentInformation" : [ { "StudentName" : "David", "StudentAge" : 22 } ] }

For this, use $project along with aggregate(). The $project in aggregation passes along the documents with the requested fields to the next stage in the pipeline.Let us create a collection with documents −> db.demo762.insertOne({ ...    "_id" : { ...       "userId":101, ...       "userName":"Chris" ...    }, ..   . "countryName" : "US", ... ...    "details" : [ ...       { ...          "Name" : "Robert", ...          "DueDate" : "2020-04-10" ... ...       }, ... ...       { ...     ... Read More

To fetch a specific value from an array, use aggregate() along with $project. Let us create a collection with documents −> db.demo761.insertOne( ...    { ...       "details": [ ...          { ...             "student": { ...                "FullName": "Chris Brown" ...             } ...          } ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb034d15637cd592b2a4af1") } > db.demo761.insertOne( ...    { ...       ... Read More

To update many documents with a single query, use bulkWrite() in MongoDB. Let us create a collection with documents −> db.demo760.insertOne({id:1, details:{Value1:100, Value2:50}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb0309f5637cd592b2a4aee") } > db.demo760.insertOne({id:2, details:{Value1:60, Value2:70}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb030a15637cd592b2a4aef") } > db.demo760.insertOne({id:3, details:{Value1:80, Value2:90}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb030a15637cd592b2a4af0") }Display all documents from a collection with the help of find() method −> db.demo760.find();This will produce the following output −{ "_id" : ObjectId("5eb0309f5637cd592b2a4aee"), "id" : 1, "details" : { "Value1" : 100, "Value2" : 50 } } { "_id" : ... Read More

For this, you need to use case insensitive (i). Let us create a collection with documents −> db.demo759.insertOne({SubjectName:"MySQL"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb02ba95637cd592b2a4ae7") } > db.demo759.insertOne({SubjectName:"MongoDB"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb02baa5637cd592b2a4ae8") } > db.demo759.insertOne({SubjectName:"mongodb"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb02baf5637cd592b2a4ae9") } > db.demo759.insertOne({SubjectName:"MONGODB"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb02bb85637cd592b2a4aea") }Display all documents from a collection with the help of find() method −> db.demo759.find();This will produce the following output −{ "_id" : ObjectId("5eb02ba95637cd592b2a4ae7"), "SubjectName" : "MySQL" } { "_id" : ObjectId("5eb02baa5637cd592b2a4ae8"), "SubjectName" : "MongoDB" } { "_id" ... Read More

For this, you can use $out along with aggregate() and $unwind. Let us create a collection with documents −> db.demo757.insertOne( ...    { ...       "id": 101, ...       "Name": ["John", "Bob", "Chris"] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb025745637cd592b2a4ae2") } > db.demo757.insertOne( ...    { ...       "id": 102, ...       "Name": ["David"] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb025755637cd592b2a4ae3") }Display all documents from a collection with the help of find() method −> db.demo757.find();This will produce the ... Read More

To check for duplicates in an array, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo756.insertOne({"SubjectName":["MySQL", "MongoDB", "Java"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb01e0d5637cd592b2a4add") } > db.demo756.insertOne({"SubjectName":["MongoDB", "MySQL", "MongoDB", "C", "C+", "MySQL"]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eb01e2b5637cd592b2a4ade") }Display all documents from a collection with the help of find() method −> db.demo756.find();This will produce the following output −{ "_id" : ObjectId("5eb01e0d5637cd592b2a4add"), "SubjectName" : [ "MySQL", "MongoDB", "Java" ] } { "_id" : ObjectId("5eb01e2b5637cd592b2a4ade"), "SubjectName" : [ "MongoDB", "MySQL", "MongoDB", "C", "C+", "MySQL" ] }Following is the query to check for ... Read More

To sort, use sort() in MongoDB. Let us create a collection with documents −> db.demo755.insertOne({"Value":10}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e72a930c785c834e572") } > db.demo755.insertOne({"Value":10.5}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e75a930c785c834e573") } > db.demo755.insertOne({"Value":9.5}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e79a930c785c834e574") } > db.demo755.insertOne({"Value":12.5}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e7fa930c785c834e575") } > db.demo755.insertOne({"Value":11.5}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e87a930c785c834e576") } > db.demo755.insertOne({"Value":6}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9e97a930c785c834e577") }Display all documents from a collection with the help of find() method −> db.demo755.find();This will produce ... Read More

Let us create a collection with documents −> db.demo754.insertOne({"DateOfBirth":new Date("2000-05-03")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9b2da930c785c834e56f") } > db.demo754.insertOne({"DateOfBirth":new Date("2010-01-21")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9b34a930c785c834e570") } > db.demo754.insertOne({"DateOfBirth":new Date("2018-05-03")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5eae9b3da930c785c834e571") }Display all documents from a collection with the help of find() method −> db.demo754.find();This will produce the following output −{ "_id" : ObjectId("5eae9b2da930c785c834e56f"), "DateOfBirth" : ISODate("2000-05-03T00:00:00Z") } { "_id" : ObjectId("5eae9b34a930c785c834e570"), "DateOfBirth" : ISODate("2010-01-21T00:00:00Z") } { "_id" : ObjectId("5eae9b3da930c785c834e571"), "DateOfBirth" : ISODate("2018-05-03T00:00:00Z") }Following is the query to convert date of birth to age −> db.demo754.aggregate( ... Read More

To filter specific values, use $filter in MongoDB. Let us create a collection with documents −> db.demo751.insertOne( ...    { ...       _id: 101, ...       details: [ ...          { Name: "Robert", id:110, Age:21}, ...          { Name: "Rae", id:110, Age:22}, ...          {Name: "Ralph", id:116, Age:23} ...       ] ...    } ... ); { "acknowledged" : true, "insertedId" : 101 }Display all documents from a collection with the help of find() method −> db.demo751.find().pretty();This will produce the following output −{    "_id" ... Read More