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Found 1659 Articles for Big Data Analytics
98 Views
The $or operator performs a logical OR operation on an array of two or more expressions. Let us create a collection with documents −> db.demo674.insertOne({Name:"Chris", Age:21}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3f33604263e90dac943eb") } > db.demo674.insertOne({Name:"David", Age:23}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3f33c04263e90dac943ec") } > db.demo674.insertOne({Name:"Bob", Age:21}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3f34204263e90dac943ed") } > db.demo674.insertOne({Name:"John", Age:24}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3f34804263e90dac943ee") }Display all documents from a collection with the help of find() method −> db.demo674.find();This will produce the following output −{ "_id" : ObjectId("5ea3f33604263e90dac943eb"), "Name" : "Chris", ... Read More
58 Views
Use max field in order to limit the number of documents in the collection. Following is the query to use the max field in the capped collection −> db.createCollection("demo673", { capped : true, size : 100, max :50 } ) { "ok" : 1 }Let us create a collection with documents −> db.demo673.insertOne({Name:"John", Age:23}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3ec7304263e90dac943e8") } > db.demo673.insertOne({Name:"Bob", Age:21}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3ec7804263e90dac943e9") } > db.demo673.insertOne({Name:"David", Age:20}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3ec7f04263e90dac943ea") }Display all documents from a collection with the help of find() ... Read More
191 Views
To fetch a specific document, use dot notation in MongoDB find(). Let us create a collection with documents −> db.demo672.insertOne({Brand:[{CategoryName:"Mobile", "Name":"Oppo"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3ea9b04263e90dac943e5") } > db.demo672.insertOne({Brand:[{CategoryName:"Mobile", "Name":"Samsung"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3eaa404263e90dac943e6") } > db.demo672.insertOne({Brand:[{CategoryName:"Mobile", "Name":"OnePlus"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3eacc04263e90dac943e7") }Display all documents from a collection with the help of find() method −> db.demo672.find();This will produce the following output −{ "_id" : ObjectId("5ea3ea9b04263e90dac943e5"), "Brand" : [ { "CategoryName" : "Mobile", "Name" : "Oppo" } ] } { "_id" : ObjectId("5ea3eaa404263e90dac943e6"), "Brand" : [ { ... Read More
579 Views
To get fields from multiple sub-documents, use MongoDB aggregate with $unwind. Let us create a collection with documents −> db.demo671.insertOne( ... { ... ... "details" : [ ... { ... "id" : "1" ... }, ... { ... CountryName:"US", ... "details1" : [ ... { ... "id" : "1" ... }, ... { ... "id" : "2" ... } ... ] ... ... Read More
725 Views
To access subdocuments in MongoDB, use find() with dot notation. Let us create a collection with documents −> db.demo670.insertOne({ ... id:101, ... "details": ... { ... Name:"Chris", ... Age:21, ... CountryName:"US", ... SubjectName:"MongoDB" ... } ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5ea3e31d04263e90dac943de") } > db.demo670.insertOne({ id:102, "details": { Name:"David", Age:22, CountryName:"UK", SubjectName:"MySQL" } } ); { "acknowledged" : true, "insertedId" : ObjectId("5ea3e33604263e90dac943df") }Display all documents from a collection with the help of find() method −> db.demo670.find();This will produce the following output −{ "_id" : ObjectId("5ea3e31d04263e90dac943de"), "id" : 101, "details" : { "Name" ... Read More
91 Views
To get the maximum element from the collection, sort in descending order with limit. Let us create a collection with documents −> > db.demo669.insertOne({"Marks":76}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3133c04263e90dac943d9") } > db.demo669.insertOne({"Marks":55}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3133f04263e90dac943da") } > db.demo669.insertOne({"Marks":89}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3134204263e90dac943db") } > db.demo669.insertOne({"Marks":88}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3134504263e90dac943dc") } > db.demo669.insertOne({"Marks":79}); { "acknowledged" : true, "insertedId" : ObjectId("5ea3134e04263e90dac943dd") }Display all documents from a collection with the help of find() method −> db.demo669.find();This will produce the following output ... Read More
130 Views
Use $all for array match. The $all operator selects the documents where the value of a field is an array that contains all the specified elements. Let us create a collection with documents −> db.demo668.createIndex({"ListOfSubject":1}); { "createdCollectionAutomatically" : true, "numIndexesBefore" : 1, "numIndexesAfter" : 2, "ok" : 1 } > db.demo668.insert({"ListOfSubject":["MySQL", "Java", "C"]}); WriteResult({ "nInserted" : 1 }) > db.demo668.insert({"ListOfSubject":["MongoDB", "Python", "C++"]}); WriteResult({ "nInserted" : 1 }) > db.demo668.insert({"ListOfSubject":["C#", "Spring", "Hibernate", "MongoDB"]}); WriteResult({ "nInserted" : 1 })Display all documents from a collection with the help of find() method −> db.demo668.find();This will produce the following output −{ ... Read More
290 Views
The ObjectId does not accept the seed string. You need to use _id − StringValue. Let us create a collection with documents −> db.demo667.insertOne({_id:"Chris"}); { "acknowledged" : true, "insertedId" : "Chris" } > db.demo667.insertOne({_id:"David"}); { "acknowledged" : true, "insertedId" : "David" } > db.demo667.insertOne({_id:"Chris"}); 2020-04-23T22:01:23.268+0530 E QUERY [js] WriteError: E11000 duplicate key error collection: test.demo667 index: _id_ dup key: { : "Chris" } : WriteError({ "index" : 0, "code" : 11000, "errmsg" : "E11000 duplicate key error collection: test.demo667 index: _id_ dup key: { : \"Chris\" }", "op" : { "_id" : ... Read More
2K+ Views
To display only the employee names with specific salaries, set the salaries in MongoDB $in and fetch the names. Let us create a collection with documents> db.demo666.insertOne({"EmployeeName":"John", "EmployeeSalary":25000}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1c04824113ea5458c7d0d") } > db.demo666.insertOne({"EmployeeName":"Chris", "EmployeeSalary":35000}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1c05524113ea5458c7d0e") } > db.demo666.insertOne({"EmployeeName":"David", "EmployeeSalary":65000}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1c06024113ea5458c7d0f") } > db.demo666.insertOne({"EmployeeName":"Carol", "EmployeeSalary":40000}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1c06f24113ea5458c7d10") }Display all documents from a collection with the help of find() method −> db.demo666.find();This will produce the following output −{ "_id" : ObjectId("5ea1c04824113ea5458c7d0d"), "EmployeeName" ... Read More
83 Views
To search for ranges, use sort() with limit(). Let us create a collection with documents −> db.demo665.insertOne({"Value":10}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1bf1424113ea5458c7d08") } > db.demo665.insertOne({"Value":15}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1bf1b24113ea5458c7d09") } > db.demo665.insertOne({"Value":55}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1bf1e24113ea5458c7d0a") } > db.demo665.insertOne({"Value":25}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1bf2324113ea5458c7d0b") } > db.demo665.insertOne({"Value":20}); { "acknowledged" : true, "insertedId" : ObjectId("5ea1bf2b24113ea5458c7d0c") }Display all documents from a collection with the help of find() method −> db.demo665.find();This will produce the following output −{ "_id" : ObjectId("5ea1bf1424113ea5458c7d08"), "Value" : 10 ... Read More