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For this, use $slice. Let us create a collection with documents −> db.demo594.insertOne( ... { ... id:1, ... details:[ ... {Name:"Chris", Age:21}, ... {Name:"Bob", Age:20}, ... {Name:"David", Age:23}, ... {Name:"Sam", Age:22} ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e933459fd2d90c177b5bcdd") }Display all documents from a collection with the help of find() method −> db.demo594.find();This will produce the following output −{ "_id" : ObjectId("5e933459fd2d90c177b5bcdd"), "id" : 1, "details" ... Read More
To fetch specific multiple documents in MongoDB, use $in. Let us create a collection with documents −> db.demo593.insertOne({id:1, "Name":"Chris"});{ "acknowledged" : true, "insertedId" : ObjectId("5e93177dfd2d90c177b5bcd9") } > db.demo593.insertOne({id:2, "Name":"John"});{ "acknowledged" : true, "insertedId" : ObjectId("5e931785fd2d90c177b5bcda") } > db.demo593.insertOne({id:3, "Name":"Bob"});{ "acknowledged" : true, "insertedId" : ObjectId("5e93178cfd2d90c177b5bcdb") } > db.demo593.insertOne({id:4, "Name":"Sam"});{ "acknowledged" : true, "insertedId" : ObjectId("5e931792fd2d90c177b5bcdc") }Display all documents from a collection with the help of find() method −> db.demo593.find();This will produce the following output −{ "_id" : ObjectId("5e93177dfd2d90c177b5bcd9"), "id" : 1, "Name" : "Chris" } { "_id" : ObjectId("5e931785fd2d90c177b5bcda"), "id" : 2, "Name" : "John" } ... Read More
To match documents that contain an array field, use the $elemMatch operator. Let us create a collection with documents −> db.demo592.insertOne( ... { ... "id":101, ... "details" : [ ... { "Name" : "Chris", "Value" : "200"}, ... {"Name" : "David", "Value" : "800"} ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e930d8ffd2d90c177b5bcd6") } > db.demo592.insertOne( ... { ... id:102, ... "details" : [ ... { "Name" : "Chris", "Value" ... Read More
To fetch a value from the nested document, use dot notation. Let us create a collection with documents −> db.demo591.insert([ ... { "Name": "John", "Age": 23 }, ... {"Name": "Carol", "Age": 26}, ... { "Name": "Robert", "Age": 29, ... details:[ ... { ... Email:"Robert@gmail.com", CountryName:"US"}, {"Post":35} ... ]} ... ]); BulkWriteResult({ "writeErrors" : [ ], "writeConcernErrors" : [ ], "nInserted" : 3, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] ... Read More
Let us create a collection with documents −> db.demo590.insert([ ... { "Name": "Chris", "Age": 21 }, ... {"Name": "Bob", "Age": 20}, ... { "Name": "Sam", "Age": 19 } ... ]); BulkWriteResult({ "writeErrors" : [ ], "writeConcernErrors" : [ ], "nInserted" : 3, "nUpserted" : 0, "nMatched" : 0, "nModified" : 0, "nRemoved" : 0, "upserted" : [ ] })Display all documents from a collection with the help of find() method −> db.demo590.find();This will produce the following output −{ "_id" : ObjectId("5e92d514fd2d90c177b5bcd0"), "Name" : "Chris", "Age" : 21 } { ... Read More
To check equality and fetch the documents, use $where in MongoDB. Let us create a collection with documents −> db.demo589.insertOne({deliveryAddress:"US", billingAddress:"UK"});{ "acknowledged" : true, "insertedId" : ObjectId("5e92c117fd2d90c177b5bccc") } > db.demo589.insertOne({deliveryAddress:"US", billingAddress:"US"});{ "acknowledged" : true, "insertedId" : ObjectId("5e92c11bfd2d90c177b5bccd") } > db.demo589.insertOne({deliveryAddress:"US", billingAddress:"AUS"});{ "acknowledged" : true, "insertedId" : ObjectId("5e92c11ffd2d90c177b5bcce") } > db.demo589.insertOne({deliveryAddress:"UK", billingAddress:"US"});{ "acknowledged" : true, "insertedId" : ObjectId("5e92c127fd2d90c177b5bccf") }Display all documents from a collection with the help of find() method −> db.demo589.find();This will produce the following output −{ "_id" : ObjectId("5e92c117fd2d90c177b5bccc"), "deliveryAddress" : "US", "billingAddress" : "UK" } { "_id" : ObjectId("5e92c11bfd2d90c177b5bccd"), "deliveryAddress" : "US", "billingAddress" : ... Read More
To gather a unique array items, use distinct(). Let us create a collection with documents −> db.demo588.insertOne({"CountryName":["US","AUS","UK","US","UK","AUS"]});{ "acknowledged" : true, "insertedId" : ObjectId("5e92bbd2fd2d90c177b5bccb") }Display all documents from a collection with the help of find() method −> db.demo588.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e92bbd2fd2d90c177b5bccb"), "CountryName" : [ "US", "AUS", "UK", "US", "UK", "AUS" ] }Following is the query to gather unique array item −> db.demo588.distinct("CountryName");This will produce the following output −[ "AUS", "UK", "US" ]
To append subdocuments, use $push in MongoDB. The update() is used to update. Let us create a collection with documents −> db.demo587.insertOne({"id":101, "details":[{Name:"Chris", Age:21, Marks:57}]});{ "acknowledged" : true, "insertedId" : ObjectId("5e92ba01fd2d90c177b5bcc9") } > db.demo587.insertOne({"id":102, "details":[{Name:"Bob", Age:22, Marks:78}]});{ "acknowledged" : true, "insertedId" : ObjectId("5e92ba0efd2d90c177b5bcca") }Display all documents from a collection with the help of find() method −> db.demo587.find();This will produce the following output −{ "_id" : ObjectId("5e92ba01fd2d90c177b5bcc9"), "id" : 101, "details" : [ { "Name" : "Chris", "Age" : 21, "Marks" : 57 } ] } { "_id" : ObjectId("5e92ba0efd2d90c177b5bcca"), "id" : 102, "details" : [ { "Name" : ... Read More
Let us create a collection with documents −> db.demo586.insertOne( ... {"details": [ ... { ... "Name":"Chris", ... "Marks":71 ... }, ... { ... "Name":"Chris", ... "Marks":61 ... }, ... { ... "Name":"David", ... "Marks":81 ... } ... ... ] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e9200fefd2d90c177b5bcc7") } > db.demo586.insertOne( ... Read More
To manually add value, use $push in MongoDB. Let us create a collection with documents −> db.demo585.insert({ ... firstName: 'John', ... lastName: 'Doe', ... SubjectName:"MongoDB", ... Marks: [59] ... }); WriteResult({ "nInserted" : 1 }) > db.demo585.insert({ ... firstName: 'Chris', ... lastName: 'Brown', ... SubjectName:"MySQL", ... Marks: [79] ... }); WriteResult({ "nInserted" : 1 })Display all documents from a collection with the help of find() method−> db.demo585.find();This will produce the following output −{ "_id" : ObjectId("5e91fd80fd2d90c177b5bcc3"), "firstName" : "John", "lastName" : "Doe", "SubjectName" : "MongoDB", "Marks" : [ 59 ] } { ... Read More