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Found 6702 Articles for Database
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
135 Views
To update a single list item, use positional operator($). Let us first create a collection with documents −> db.updateASingleListDemo.insertOne({ _id:1, "EmployeeName":"Chris", "EmployeeDetails": [ {"EmployeeId":"EMP-101", "EmployeeSalary": 18999 }] }); { "acknowledged" : true, "insertedId" : 1 }Following is the query to display all documents from a collection with the help of find() method −> db.updateASingleListDemo.find().pretty();This will produce the following output −{ "_id" : 1, "EmployeeName" : "Chris", "EmployeeDetails" : [ { "EmployeeId" : "EMP-101", "EmployeeSalary" : 18999 } ] }Following is the query ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
89 Views
To retrieve array values, use dot(.) notation. Let us first create a collection with documents −> db.retrievingArrayDemo.insertOne( { "UserDetails" : [ { "UserName" : "John", "UserAge" : 23 } ], "UserCountryName" : "AUS", "UserLoginDate" : new ISODate(), "UserMessage" : "Hello" } ); { "acknowledged" : true, "insertedId" : ObjectId("5ce9718478f00858fb12e920") } > db.retrievingArrayDemo.insertOne( { "UserDetails" : [ { "UserName" : "Sam", "UserAge" : 24 } ], "UserCountryName" : "UK", "UserLoginDate" : new ISODate(), "UserMessage" : "Bye" } ); { "acknowledged" : true, "insertedId" : ObjectId("5ce9718478f00858fb12e921") }Following is the query to display all documents from a collection with the help of find() method −> db.retrievingArrayDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce9718478f00858fb12e920"), ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
699 Views
To update child objects, use $set operator. Let us first create a collection with document −>db.updateChildObjectsDemo.insertOne({"StudentName":"Chris", "StudentOtherDetails":{"StudentSubject":"MongoDB", "StudentCountryName":"AUS"}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce964e078f00858fb12e91f") }Following is the query to display all documents from a collection with the help of find() method −> db.updateChildObjectsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce964e078f00858fb12e91f"), "StudentName" : "Chris", "StudentOtherDetails" : { "StudentSubject" : "MongoDB", "StudentCountryName" : "AUS" } }Following is the query to update child objects in MongoDB −> db.updateChildObjectsDemo.update({"StudentName" : "Chris"}, {$set:{"StudentOtherDetails.StudentCountryName":"UK"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, ... Read More
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
1K+ Views
To convert a field to an array, use $set operator. Let us first create a collection with documents −> db.convertAFieldToAnArrayDemo.insertOne({"StudentSubject":"MongoDB"}); { "acknowledged" : true, "insertedId" : ObjectId("5ce92d7778f00858fb12e91d") }Following is the query to display all documents from a collection with the help of find() method −> db.convertAFieldToAnArrayDemo.find();This will produce the following output −{ "_id" : ObjectId("5ce92d7778f00858fb12e91d"), "StudentSubject" : "MongoDB" }Following is the query to convert a field to an array using update operation with $set:−> db.convertAFieldToAnArrayDemo.find().forEach(function(myDocument) { db.convertAFieldToAnArrayDemo.update( { _id: myDocument._id }, { "$set": { "StudentSubject": [myDocument.StudentSubject] } } ); })Let ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
378 Views
To remove empty fields, use deleteMany(). Let us first create a collection with documents −> db.removeEmptyFieldsDemo.insertOne({"StudentName":""}); { "acknowledged" : true, "insertedId" : ObjectId("5ce92b9578f00858fb12e919") } > db.removeEmptyFieldsDemo.insertOne({"StudentName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5ce92b9878f00858fb12e91a") } > db.removeEmptyFieldsDemo.insertOne({"StudentName":""}); { "acknowledged" : true, "insertedId" : ObjectId("5ce92b9c78f00858fb12e91b") } > db.removeEmptyFieldsDemo.insertOne({"StudentName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5ce92ba078f00858fb12e91c") }Following is the query to display all documents from a collection with the help of find() method −> db.removeEmptyFieldsDemo.find();This will produce the following output −{ "_id" : ObjectId("5ce92b9578f00858fb12e919"), "StudentName" : "" } { "_id" : ObjectId("5ce92b9878f00858fb12e91a"), "StudentName" : "Chris" ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
1K+ Views
You can use dot(.) notation for this. Let us first create a collection with documents −> db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"John", "UserLastName":"Smith"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929c778f00858fb12e916") } > > db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"Chris", "UserLastName":"Brown"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929d678f00858fb12e917") } > db.createIndexOnNestedFieldDemo.insertOne( {"UserDetails":{"UserPersonalDetails":{"UserFirstName":"David", "UserLastName":"Miller"}}}); { "acknowledged" : true, "insertedId" : ObjectId("5ce929e378f00858fb12e918") }Following is the query to display all documents from a collection with the help of find() method −> db.createIndexOnNestedFieldDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce929c778f00858fb12e916"), "UserDetails" : { ... Read More
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
93 Views
You can use find() for this. Let us first create a collection with documents −> db.findDocumentsDemo.insertOne( { _id: 101, "ProductDetails": [ { "ProductValue":100 }, { "ProductValue":120 } ] } ); { "acknowledged" : true, "insertedId" : 101 } > db.findDocumentsDemo.insertOne( { _id: 102, "ProductDetails": [ { "ProductValue":120}, { "ProductValue":120 }, { "ProductValue":120 } ] } ); { "acknowledged" ... Read More
![Smita Kapse](https://www.tutorialspoint.com/assets/profiles/13597/profile/60_103706-1512718957.jpg)
89 Views
For array concatenation, use $concatArrays operator. Let us first create a collection with documents −>db.arrayConcatenationDemo.insertOne({"TeacherName":["Chris", "Robert"], "StudentName":["Mike", "Sam"]}); { "acknowledged" : true, "insertedId" : ObjectId("5ce921c078f00858fb12e911") }Following is the query to display all documents from a collection with the help of find() method −> db.arrayConcatenationDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce921c078f00858fb12e911"), "TeacherName" : [ "Chris", "Robert" ], "StudentName" : [ "Mike", "Sam" ] }Following is the query for array concatenation −> db.arrayConcatenationDemo.aggregate([ { "$project": { ... Read More
![Anvi Jain](https://www.tutorialspoint.com/assets/profiles/13591/profile/60_98631-1512716973.jpg)
2K+ Views
Let us first create a collection with documents −> db.querySelectDemo.insertOne({UserId:100, UserName:"Chris", UserAge:25}); { "acknowledged" : true, "insertedId" : ObjectId("5ce90eb478f00858fb12e90e") } > db.querySelectDemo.insertOne({UserId:101, UserName:"Robert", UserAge:26}); { "acknowledged" : true, "insertedId" : ObjectId("5ce90ec578f00858fb12e90f") } > db.querySelectDemo.insertOne({UserId:103, UserName:"David", UserAge:27}); { "acknowledged" : true, "insertedId" : ObjectId("5ce90ed478f00858fb12e910") }Following is the query to display all documents from a collection with the help of find() method −> db.querySelectDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce90eb478f00858fb12e90e"), "UserId" : 100, "UserName" : "Chris", "UserAge" : 25 } { "_id" : ObjectId("5ce90ec578f00858fb12e90f"), "UserId" : 101, ... Read More
![Nishtha Thakur](https://www.tutorialspoint.com/assets/profiles/13598/profile/60_104893-1512719058.jpg)
358 Views
Let us first create a collection with documents −> db.updateArrayElementDemo.insertOne( { "UserDetails": [ { "UserName":"Chris", "UserAge":23 } ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5ce9029378f00858fb12e90d") }Following is the query to display all documents from a collection with the help of find() method −> db.updateArrayElementDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5ce9029378f00858fb12e90d"), "UserDetails" : [ { ... Read More