To remove document on the basis of _id in MongoDB, implement the following syntaxdb.yourCollectionName.remove({“_id”:ObjectId(“yourId”});Let us first implement the following query to create a collection with documents>db.removeDocumentOnBasisOfId.insertOne({"UserName":"Larry", "UserAge":23, "UserCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986f9f330fd0aa0d2fe4a3") } >db.removeDocumentOnBasisOfId.insertOne({"UserName":"Sam", "UserAge":21, "UserCountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986fb4330fd0aa0d2fe4a4") } >db.removeDocumentOnBasisOfId.insertOne({"UserName":"Chris", "UserAge":24, "UserCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986fc0330fd0aa0d2fe4a5") } >db.removeDocumentOnBasisOfId.insertOne({"UserName":"Robert", "UserAge":26, "UserCountryName":"UK"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986fcf330fd0aa0d2fe4a6") } >db.removeDocumentOnBasisOfId.insertOne({"UserName":"David", "UserAge":28, "UserCountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986fed330fd0aa0d2fe4a7") }Following is the query to display all documents from a collection ... Read More

To increment a value in nested object, you can use $inc operator. Let us first implement the following query to create a collection with documents>db.incrementValueDemo.insertOne({"StudentName":"Larry", "StudentCountryName":"US", "StudentDetails":[{"StudentSubjectName":"Math", "StudentMathMarks":79}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c986ca0330fd0aa0d2fe4a2") }Following is the query to display all documents from a collection with the help of find() method> db.incrementValueDemo.find().pretty();This will produce the following output{    "_id" : ObjectId("5c986ca0330fd0aa0d2fe4a2"),    "StudentName" : "Larry",    "StudentCountryName" : "US",    "StudentDetails" : [       {          "StudentSubjectName" : "Math",          "StudentMathMarks" : 79       }    ] ... Read More

Use aggregate() method to get the duplicate value of a field. Let us first create a collection with documents using the following query> db.findAllNonDistinctDemo.insertOne({"UserName":"John", "UserAge":28}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995078863d6ffd454bb647") } > db.findAllNonDistinctDemo.insertOne({"UserName":"Larry", "UserAge":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995081863d6ffd454bb648") } > db.findAllNonDistinctDemo.insertOne({"UserName":"Larry", "UserAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995089863d6ffd454bb649") } > db.findAllNonDistinctDemo.insertOne({"UserName":"David", "UserAge":22}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c995093863d6ffd454bb64a") } > db.findAllNonDistinctDemo.insertOne({"UserName":"John", "UserAge":26}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c99509d863d6ffd454bb64b") } > db.findAllNonDistinctDemo.insertOne({"UserName":"Robert", "UserAge":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9950a7863d6ffd454bb64c") } ... Read More

To insert current datetime in MongoDB, use the $setOnInsert operator. Let us first implement the following query to create a collection with documents>db.addCurrentDateTimeDemo.insertOne({"StudentName":"John", "StudentAdmissionDate":new Date("2012-01-21") }); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97ae45330fd0aa0d2fe49f") } >db.addCurrentDateTimeDemo.insertOne({"StudentName":"Carol", "StudentAdmissionDate":new Date("2013-05-24") }); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97ae54330fd0aa0d2fe4a0") } >db.addCurrentDateTimeDemo.insertOne({"StudentName":"Carol", "StudentAdmissionDate":new Date("2019-07-26") }); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97ae5f330fd0aa0d2fe4a1") }Following is the query to display all documents from a collection with the help of find() method> db.addCurrentDateTimeDemo.find().pretty();This will produce the following output{    "_id" : ObjectId("5c97ae45330fd0aa0d2fe49f"),    "StudentName" : "John",    "StudentAdmissionDate" : ISODate("2012-01-21T00:00:00Z") } { ... Read More

To search a document in MongoDB by _id, you need to call ObjectId(). Let us first see the syntaxdb.yourCollectionName.find({"_id":ObjectId("yourId")}).pretty();To understand the concept and search a document, let us implement the following query to create a collection with documents> db.searchDocumentDemo.insertOne({"UserId":1, "UserName":"Larry"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97a8e4330fd0aa0d2fe487") } > db.searchDocumentDemo.insertOne({"UserId":2, "UserName":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97a8ea330fd0aa0d2fe488") } > db.searchDocumentDemo.insertOne({"UserId":3, "UserName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97a8f1330fd0aa0d2fe489") } > db.searchDocumentDemo.insertOne({"UserId":4, "UserName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c97a8fa330fd0aa0d2fe48a") } > db.searchDocumentDemo.insertOne({"UserId":5, "UserName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ... Read More

To create a double nested array in MongoDB, let us implement the query to create a collection with documents. Within that, we have created a double nested array that displays Student Details, with the project name and technologies used to develop the same project:> db.doubleNestedArrayDemo.insertOne( ... { ...    "StudentId" : "1000", ...    "StudentName" : "Larry", ...    "StudentDetails" : [ ...    { ...       "ProjectName" : "Online Banking", ...       "ProjectDetails" : [ ...       { ...          "TechnologyUsed" : "Java" ...       }, ...   ... Read More

The _id in MongoDB is a field, which is mandatory. In MongoDB, each document stored in a collection requires a unique _id field that acts as a primary key. Following is the syntax to get the array of all the ids i.e. _id in MongoDBdb.yourCollectionName.find({ _id : { $in : [yourValue1, yourValue2, yourValue3, .......N] } } );Let us first implement the following query to create a collection with documents> db.selectInWhereIdDemo.insertOne({"_id":23}); { "acknowledged" : true, "insertedId" : 23 } > db.selectInWhereIdDemo.insertOne({"_id":28}); { "acknowledged" : true, "insertedId" : 28 } > db.selectInWhereIdDemo.insertOne({"_id":45}); { "acknowledged" : true, "insertedId" : 45 } > db.selectInWhereIdDemo.insertOne({"_id":75}); ... Read More

In MongoDB, there is no concept of columns since MongoDB is schema-less and does not contain tables. It contains the concept of collections and a collection has different types of documents to store items.Let us see the syntax −db.yourCollectionName.insertOne({“YourFieldName”:yourValue, “yourFieldName”:”yourValue”, .......N});If you want a single record from a collection, you can use findOne() and in order to get all records from the collection, you can use find().The syntax is as follows −db.yourCollectionName.findOne(); //Get Single Record db.yourCollectionName.find(); // Get All RecordTo understand the above syntax, let us create a collection with the document. The query to create a collection with a ... Read More

You can switch from one database to another using the use command. Here, we are using the collection in the “test” database. Let us insert that collection in another database with the name “sample”.To understand further, let us create a collection with the document. The query to create a collection with a document is as follows −> db.insertOneRecordDemo.insertOne({"UserName":"Larry", "UserAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9534de16f542d757e2b452") } > db.insertOneRecordDemo.insertOne({"UserName":"Chris", "UserAge":26}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9534e816f542d757e2b453") } > db.insertOneRecordDemo.insertOne({"UserName":"David", "UserAge":25}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9534f116f542d757e2b454") }Display all documents from a collection ... Read More

MongoDB order the docs in one collection with the help of a $natural operator. It stores the document as it is when we get from find(). The default order is $natural. Let us now see the syntax −db.yourCollectionName.find().sort({ "$natural": 1 });To understand the above syntax, let us create a collection with the document. The query to create a collection with a document is as follows −> db.orderDocsDemo.insertOne({"UserScore":87}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9531a316f542d757e2b44b") } > db.orderDocsDemo.insertOne({"UserScore":98}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9531a816f542d757e2b44c") } > db.orderDocsDemo.insertOne({"UserScore":99}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9531b216f542d757e2b44d") ... Read More