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Found 1669 Articles for Big Data Analytics
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To update the objects in a document’s array, you need to use update() method. To understand the update() method, let us create a collection with document. The query to create a collection with document is as follows:> db.updateObjects.insertOne({"CustomerId":1, "CustomerName":"Larry", "TotalItems":100, ... "ItemDetails":[ ... { ... "NameOfItem":"Item_1", ... "Amount":450 ... }, ... { ... "NameOfItem":"Item_2", ... "Amount":500 ... }, ... { ... "NameOfItem":"Item_3", ... "Amount":200 ... } ... ] ... } ... );The following is the output:{ "acknowledged" : true, "insertedId" : ObjectId("5c6d688b0c3d5054b766a769") }Now you can display documents from a collection with the help of find() method. The query ... Read More
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You can use aggregate and unwind the array list before applying match. To understand the above concept, let us create a collection with documents. The query to create a collection with document is as follows:> db.filterArray.insertOne( { "L": [{ "N":1 }, { "N":2 } , { "N":3 }, { "N":4 }, { "N":5 } ]});The following is visible after running the above query:{ "acknowledged" : true, "insertedId" : ObjectId("5c6d63f2734e98fc0a434aeb") }Display document from a collection with the help of find() method. The query is as follows:> db.filterArray.find().pretty();The following is the output:{ "_id" : ObjectId("5c6d63f2734e98fc0a434aeb"), "L" : [ ... Read More
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To get a random record from MongoDB, you can use aggregate function. The syntax is as follows:db.yourCollectionName.aggregate([{$sample:{size:1}}]);To understand the above syntax, let us create a collection with some documents. The query to create collection is as follows:>db.employeeInformation.insert({"EmployeeId":1, "EmployeeName":"Maxwell", "EmployeeAge":26}); WriteResult({ "nInserted" : 1 }) >db.employeeInformation.insert({"EmployeeId":2, "EmployeeName":"David", "EmployeeAge":25}); WriteResult({ "nInserted" : 1 }) >db.employeeInformation.insert({"EmployeeId":3, "EmployeeName":"Carol", "EmployeeAge":24}); WriteResult({ "nInserted" : 1 }) >db.employeeInformation.insert({"EmployeeId":4, "EmployeeName":"Bob", "EmployeeAge":28}); WriteResult({ "nInserted" : 1 }) >db.employeeInformation.insert({"EmployeeId":5, "EmployeeName":"Sam", "EmployeeAge":27); WriteResult({ "nInserted" : 1 })Now you can display all documents from a collection with the help of find() method. The query is as follows:> db.employeeInformation.find().pretty();The following is the output:{ ... Read More
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You can use $where operator along with find() method to compare two fields in MongoDB. The syntax is as follows:db.yourCollectionName.find({$where:”yourCondition”}).pretty();To understand the above syntax, let us create a collection with some documents. The query to create a collection with documents is as follows:>db.compareTwoFields.insert({"Id":1, "FullName":{"FirstName":"John", "LastName":"Smith"}, "BranchName":"ComputerScience"}); WriteResult({ "nInserted" : 1 }) >db.compareTwoFields.insert({"Id":2, "FullName":{"FirstName":"Smith", "LastName":"Smith"}, "BranchName":"Civil"}); WriteResult({ "nInserted" : 1 }) >db.compareTwoFields.insert({"Id":3, "FullName":{"FirstName":"David", "LastName":"Smith"}, "BranchName":"Mechanical"}); WriteResult({ "nInserted" : 1 })Now you can display all documents from a collection with the help of find() method. The query is as follows:> db.compareTwoFields.find().pretty();The following is the output:{ "_id" : ObjectId("5c6c237568174aae23f5ef64"), ... Read More
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The syntax to get names of all keys in the collection is as follows:var yourVariableName1=db.yourCollectionName.findOne(); for(var yourVariableName 2 in yourVariableName1) { print(yourVariableName); }To understand the above syntax, let us create a collection with documents. The collection name we are creating is “studentGetKeysDemo”.The following is the query to create documents:>db.studentGetKeysDemo.insert({"StudentId":1, "StudentName":"Larry", "StudentAge":23, "StudentAddress":"US", ... "StudentHobby":["Cricket", "Football", "ReadingNovel"], "StudentMathMarks":89, "StudentDOB":ISODate('1998-04-06')});The following is the output:WriteResult({ "nInserted" : 1 })Display all documents from a collection with the help of find() method. The query is as follows:> db.studentGetKeysDemo.find().pretty();The following is the output:{ "_id" : ObjectId("5c6c12dd68174aae23f5ef5f"), "StudentId" : 1, "StudentName" : ... Read More
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You can easily query MongoDB with “like”:db.yourCollectionName.find({"yourFieldName" : /.*yourMatchingValue.*/}).pretty();To understand the above syntax, let us create a collection with some documents. Here, we have a collection with the name ‘employee’. The query is as follows:> db.employee.insert({"EmployeeName":"John", "EmployeeSalary":450000}); WriteResult({ "nInserted" : 1 }) > db.employee.insert({"EmployeeName":"Carol", "EmployeeSalary":150000}); WriteResult({ "nInserted" : 1 }) > db.employee.insert({"EmployeeName":"James", "EmployeeSalary":550000}); WriteResult({ "nInserted" : 1 }) > db.employee.insert({"EmployeeName":"Jace", "EmployeeSalary":670000}); WriteResult({ "nInserted" : 1 }) > db.employee.insert({"EmployeeName":"Larry", "EmployeeSalary":1000000}); WriteResult({ "nInserted" : 1 })Now you can display all documents from a collection using find() method. The query is as follows:> db.employee.find().pretty();The following is the output:{ "_id" : ObjectId("5c6c0b2e68174aae23f5ef59"), ... Read More
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Use operator $gte and $lt to find objects between two dates in MongoDB. To understand these operators, let us create a collection.Creating a collection here:>db.order.insert({"OrderId":1, "OrderAddrees":"US", "OrderDateTime":ISODate("2019-02-19")}; WriteResult({ "nInserted" : 1 }) >db.order.insert({"OrderId":2, "OrderAddrees":"UK", "OrderDateTime":ISODate("2019-02-26")}; WriteResult({ "nInserted" : 1 })Display all documents from the collection with the help of find() method. The query is as follows:> db.order.find().pretty();The following is the output:{ "_id" : ObjectId("5c6c072068174aae23f5ef57"), "OrderId" : 1, "OrderAddrees" : "US", "OrderDateTime" : ISODate("2019-02-19T00:00:00Z") } { "_id" : ObjectId("5c6c073568174aae23f5ef58"), "OrderId" : 2, "OrderAddrees" : "UK", "OrderDateTime" : ISODate("2019-02-26T00:00:00Z") }Here is the query ... Read More
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You can use aggregate function to update MongoDB field using the value of another field. Here, we will create two collections:namestudentInformation CollectionThe query to create first collection with documents is as follows:> db.name.insert({"FirstName":"John", "LastName":"Smith"}); WriteResult({ "nInserted" : 1 })Now you can display all documents from the collection with the help of find() method. The query is as follows:> db.name.find().pretty();The following is the output that displays the collection “name” documents:{ "_id" : ObjectId("5c6c00dd68174aae23f5ef55"), "FirstName" : "John", "LastName" : "Smith" } CollectionThe query to create second collection with documents is as follows:> db.studentInformation.insert({"StudentFirstName":"Carol", "StudentLastName":"Taylor"}); WriteResult({ "nInserted" : 1 })Now ... Read More
231 Views
You can use projection operator $elemMatch to filter in queried element in an object array in MongoDB collection. To retrieve only the queried element in an object array in MongoDB, let us first create a collection with documents object array.The query is as follows:> db.objectArray.insert({"Persons":[ {"PersonName":"Adam", "PersonSalary":25000}, {"PersonName":"Larry", "PersonSalary":27000 }]}); WriteResult({ "nInserted" : 1 }) > db.objectArray.insert({"Persons":[ {"PersonName":"David", "PersonSalary":32000}, {"PersonName":"Carol", "PersonSalary":77000 }]}); WriteResult({ "nInserted" : 1 })Now you can display all the documents with the help of find(). The query is as follows:> db.objectArray.find().pretty();The following is the output:{ "_id" : ObjectId("5c6bfadc68174aae23f5ef53"), "Persons" ... Read More
1K+ Views
To retrieve documents from a collection in MongoDB, you need to use find() method. The syntax is as follows:db.yourCollectionName.find();The above syntax will return all the documents from a collection in MongoDB. To understand the above syntax, let us create a collection with documents. The query to create documents are as follows:> db.retrieveAllStudents.insertOne({"StudentId":"STUD101", "StudentName":"David", "StudentAge":24}); { "acknowledged" : true, "insertedId" : ObjectId("5c6bf5cf68174aae23f5ef4e") } > db.retrieveAllStudents.insertOne({"StudentId":"STUD102", "StudentName":"Carol", "StudentAge":22}); { "acknowledged" : true, "insertedId" : ObjectId("5c6bf5e968174aae23f5ef4f") } > db.retrieveAllStudents.insertOne({"StudentId":"STUD103", "StudentName":"Maxwell", "StudentAge":25}); { "acknowledged" : true, "insertedId" : ObjectId("5c6bf5f768174aae23f5ef50") } > db.retrieveAllStudents.insertOne({"StudentId":"STUD104", "StudentName":"Bob", "StudentAge":23}); { "acknowledged" : true, "insertedId" : ... Read More
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