You need to use multi:true to update multiple documents. Let us first create a collection with documents −> db.multiUpdateDemo.insertOne({"ClientName":"John", "ClientAge":29}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5bc0b50a6c6dd317adc8") } > db.multiUpdateDemo.insertOne({"ClientName":"Carol", "ClientAge":31}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5bc1b50a6c6dd317adc9") } > db.multiUpdateDemo.insertOne({"ClientName":"John", "ClientAge":39}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5bc3b50a6c6dd317adca") } > db.multiUpdateDemo.insertOne({"ClientName":"John", "ClientAge":41}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5bc5b50a6c6dd317adcb") } > db.multiUpdateDemo.insertOne({"ClientName":"David", "ClientAge":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5bc6b50a6c6dd317adcc") }Following is the query to display all documents from a collection with the help of find() method −> db.multiUpdateDemo.find().pretty();This ... Read More

You can use $set operator for this. Following is the syntax −db.yourCollectionName.update({"_id" : yourObjectId }, {$set: { "yourOuterFieldName.anyInnerFieldName": yourValue}});Let us first create a collection with documents −> db.pushNewKeyDemo.insertOne({"UserId":100, "UserDetails":{}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda58f5b50a6c6dd317adbf") }Following is the query to display all documents from a collection with the help of find() method −> db.pushNewKeyDemo.find();This will produce the following output −{ "_id" : ObjectId("5cda58f5b50a6c6dd317adbf"), "UserId" : 100, "UserDetails" : { } }Following is the query to push new key element into subdocument of MongoDB −> db.pushNewKeyDemo.update({"_id" : ObjectId("5cda58f5b50a6c6dd317adbf")}, {$set: {    "UserDetails.UserName": "David Miller"}}); WriteResult({ "nMatched" : 1, ... Read More

You can use $pull operator to remove a string from an array. Let us first create a collection with documents −> db.removeAStringDemo.insertOne({"Score":[45, 67, 89, "John", 98, 99, 67]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda5224b50a6c6dd317adbd") }Following is the query to display all documents from a collection with the help of find() method −> db.removeAStringDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cda5224b50a6c6dd317adbd"),    "Score" : [       45,       67,       89,       "John",       98,       99,       67    ] ... Read More

You can use $where operator for this. Let us first create a collection with documents −>db.veryStrictDocumentDemo.insertOne({"StudentFirstName":"John", "StudentLastName":"Doe", "StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda4bcdb50a6c6dd317adb8") } > db.veryStrictDocumentDemo.insertOne({"StudentFirstName":"Larry"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda4bdbb50a6c6dd317adb9") } >db.veryStrictDocumentDemo.insertOne({"StudentFirstName":"David", "StudentLastName":"Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda4becb50a6c6dd317adba") } > db.veryStrictDocumentDemo.insertOne({"StudentFirstName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda4bfbb50a6c6dd317adbb") } > db.veryStrictDocumentDemo.insertOne({"StudentFirstName":"Bob", "StudentLastName":"Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cda4c6db50a6c6dd317adbc") }Following is the query to display all documents from a collection with the help of find() method −> db.veryStrictDocumentDemo.find();This will produce the following output ... Read More

You can use aggregate framework. Let us first create a collection with documents −> db.getArrayDemo.insertOne(    {       "CustomerId":101,       "CustomerDetails":[          {             "CustomerName":"Larry",             "CustomerFriendDetails":[                {                   "CustomerFriendName":"Sam"                },                {                   "CustomerFriendName":"Robert"                }         ... Read More

You can use $gt operator for this. Let us first create a collection with documents −> db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[89, 43, 32, 45]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e9f9b50a6c6dd317adb3") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[32, 33, 34, 40]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea13b50a6c6dd317adb4") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[45, 56, 66, 69]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea25b50a6c6dd317adb5") } > db.arrayElementsNotGreaterThanDemo.insertOne({"Scores":[46, 66, 77, 88]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9ea3cb50a6c6dd317adb6") }Following is the query to display all documents from a collection with the help of find() method −> db.arrayElementsNotGreaterThanDemo.find().pretty();This will produce the following output −{   ... Read More

Yes, you can use capped parameter along with max size. Following is the syntax −db.createCollection("yourCollectionName", {capped:true, size:yourSizeInBytes, max:howManyRecordsYouWant})Let us first create a collection with capped:true −> db.createCollection("limitTheNumberOfRecordsDemo", {capped:true, size:200024, max:3}) { "ok" : 1 }We will now create a collection with documents −> db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"James Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e601b50a6c6dd317adad") } > db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"Sam Williams"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e60bb50a6c6dd317adae") } > db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"David Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e612b50a6c6dd317adaf") } > db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"Carol Taylor"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9e61ab50a6c6dd317adb0") } > db.limitTheNumberOfRecordsDemo.insertOne({"ClientName":"Adam Smith"}); {    "acknowledged" ... Read More

To get particular field as a result in MongoDB, you can use findOne(). Following is the syntax −db.yourCollectionName.findOne({"yourFieldName1":yourValue}, {yourFieldName2:1});Let us first create a collection with documents −> db.particularFieldDemo.insertOne({"EmployeeName":"John Smith", "EmployeeAge":26, "EmployeeTechnology":"MongoDB"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9b4abb50a6c6dd317ada2") } > db.particularFieldDemo.insertOne({"EmployeeName":"Chris Brown", "EmployeeAge":28, "EmployeeTechnology":"Java"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9b4d2b50a6c6dd317ada3") } > db.particularFieldDemo.insertOne({"EmployeeName":"David Miller", "EmployeeAge":30, "EmployeeTechnology":"MySQL"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9b4e8b50a6c6dd317ada4") } > db.particularFieldDemo.insertOne({"EmployeeName":"John Doe", "EmployeeAge":31, "EmployeeTechnology":"C++"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9b527b50a6c6dd317ada5") }Following is the query to display all documents from a collection with the help of ... Read More

Let us first create a collection with documents wherein one of the fields is StudentName −> db.lowerCaseDemo.insertOne({"StudentName":"JOHN SMith"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a86fb50a6c6dd317ad9f") } > db.lowerCaseDemo.insertOne({"StudentName":"CAROL TAYLor"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a88fb50a6c6dd317ada0") } > db.lowerCaseDemo.insertOne({"StudentName":"DAVID Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a89fb50a6c6dd317ada1") }Following is the query to display all documents from a collection with the help of find() method −> db.lowerCaseDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd9a86fb50a6c6dd317ad9f"),    "StudentName" : "JOHN SMith" } {    "_id" : ObjectId("5cd9a88fb50a6c6dd317ada0"),    "StudentName" : "CAROL TAYLor" } { ... Read More

Use find() with dot notation to perform recursive search. Let us first create a collection with documents −> db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":101, "ClientName":"Chris"}, {"ClientId":102, "ClientName":"Robert"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a118b50a6c6dd317ad99") } > db.findOperationDemo.insertOne({"ClientDetails":[{"ClientId":110, "ClientName":"David"}, {"ClientId":112, "ClientName":"Mike"}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd9a12fb50a6c6dd317ad9a") }Following is the query to display all documents from a collection with the help of find() method −> db.findOperationDemo.find().pretty();This will produce the following output −{    "_id" : ObjectId("5cd9a118b50a6c6dd317ad99"),    "ClientDetails" : [       {          "ClientId" : 101,          "ClientName" : "Chris"       ... Read More