To access fields in a document, simply use find(). Let us create a collection with documents −> db.demo565.insertOne( ... { ...    id:101, ...    Name:"David", ...    "CountryName":"US" ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e90896739cfeaaf0b97b577") } > > db.demo565.insertOne( ... { ...    id:102, ...    Name:"Carol", ...    "CountryName":"UK" ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e90896839cfeaaf0b97b578") } > > db.demo565.insertOne( ... { ...    id:103, ...    Name:"Sam", ...    "CountryName":"AUS" ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e90896839cfeaaf0b97b579") }Display all ... Read More

To replace, use $set and positional($) operator. Let us create a collection with documents −> db.demo564.insertOne({"StudentName":["Chris", "David", "Mike", "Sam"]});{    "acknowledged" : true, "insertedId" : ObjectId("5e90880a39cfeaaf0b97b576") }Display all documents from a collection with the help of find() method −> db.demo564.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e90880a39cfeaaf0b97b576"),    "StudentName" : [       "Chris",       "David",       "Mike",       "Sam"    ] }Following is the query to replace single array value with string −> db.demo564.updateMany( ...    { "StudentName": "David" }, ...    { "$set": { "StudentName.$": "Carol Taylor" } ... Read More

To get items with a specific value, simply use find(). Let us create a collection with documents −> db.demo563.insertOne({"Name":"Chris", "Age":21, "isMarried":true}){    "acknowledged" : true, "insertedId" : ObjectId("5e8f546c54b4472ed3e8e878") } > db.demo563.insertOne({"Name":"Bob", "Age":23, "isMarried":false}){    "acknowledged" : true, "insertedId" : ObjectId("5e8f547854b4472ed3e8e879") } > db.demo563.insertOne({"Name":"Carol", "Age":23, "isMarried":true}){    "acknowledged" : true, "insertedId" : ObjectId("5e8f548b54b4472ed3e8e87a") } > db.demo563.insertOne({"Name":"Mike", "Age":21, "isMarried":true}){    "acknowledged" : true, "insertedId" : ObjectId("5e8f549454b4472ed3e8e87b") }Display all documents from a collection with the help of find() method −> db.demo563.find();This will produce the following output −{ "_id" : ObjectId("5e8f546c54b4472ed3e8e878"), "Name" : "Chris", "Age" : 21, "isMarried" : true } { "_id" : ... Read More

To search for a field, use $exists and to delete it, use $unset. The $unset operator in MongoDB deletes a particular field.Let us create a collection with documents −> db.demo562.insertOne({"Name":"Chris", "Age":21});{    "acknowledged" : true,    "insertedId" : ObjectId("5e8f4ae854b4472ed3e8e872") } > db.demo562.insertOne({"Age":20});{    "acknowledged" : true,    "insertedId" : ObjectId("5e8f4ae954b4472ed3e8e873") } > db.demo562.insertOne({"Name":"David", "Age":23});{    "acknowledged" : true,    "insertedId" : ObjectId("5e8f4aea54b4472ed3e8e874") }Display all documents from a collection with the help of find() method −> db.demo562.find();This will produce the following output −{ "_id" : ObjectId("5e8f4ae854b4472ed3e8e872"), "Name" : "Chris", "Age" : 21 } { "_id" : ObjectId("5e8f4ae954b4472ed3e8e873"), "Age" : 20 } ... Read More

To randomize unique data, use Math.random() in MongoDB. Let us create a collection with documents −> db.demo561.insertOne({EmailId:null});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f490454b4472ed3e8e86c") } > db.demo561.insertOne({EmailId:null});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f490654b4472ed3e8e86d") } > db.demo561.insertOne({EmailId:null});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f490a54b4472ed3e8e86e") }Display all documents from a collection with the help of find() method −> db.demo561.find();This will produce the following output −{ "_id" : ObjectId("5e8f490454b4472ed3e8e86c"), "EmailId" : null } { "_id" : ObjectId("5e8f490654b4472ed3e8e86d"), "EmailId" : null } { "_id" : ObjectId("5e8f490a54b4472ed3e8e86e"), "EmailId" : null }Following is the query for randomizing unique data with MongoDB −> db.demo561.find().forEach(function(doc){ ...   ... Read More

To match, use $match in MongoDB and to get data between two dates, use $gte and $lte. Let us create a collection with documents −> db.demo560.insertOne({"value1":40, "value2":40, shippingDate:new ISODate("2020-02-26")});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f3d5254b4472ed3e8e867") } > db.demo560.insertOne({"value1":20, "value2":60, shippingDate:new ISODate("2020-02-26")});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f3d5254b4472ed3e8e868") } > db.demo560.insertOne({"value1":40, "value2":70, shippingDate:new ISODate("2020-03-31")});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f3d5254b4472ed3e8e869") } > db.demo560.insertOne({"value1":40, "value2":130, shippingDate:new ISODate("2020-03-31")});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f3d5254b4472ed3e8e86a") }Display all documents from a collection with the help of find() method −> db.demo560.find();This will produce the following output −{ "_id" : ObjectId("5e8f3d5254b4472ed3e8e867"), "value1" : ... Read More

To GROUP BY array of the document, use $group. Let us create a collection with documents −>db.demo559.insertOne({details:[{Name:"Chris", Age:21}, {Name:"Bob", Age:22}, {Name:"Carol", Age:21}, {Name:"Sam", Age:21}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e8f38d954b4472ed3e8e866") }Display all documents from a collection with the help of find() method −> db.demo559.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e8f38d954b4472ed3e8e866"),    "details" : [       {          "Name" : "Chris",          "Age" : 21       },       {          "Name" : "Bob",          "Age" : ... Read More

Let us see an example and create a collection with documents −> db.demo558.insertOne( ... { ...    _id : 100, ...    CountryCode:101, ...    details: [ ...       { ...          Name:"Chris", ...          Subject:"MySQL" ...       }, ...       { ...          Name:"Chris", ...          Subject:"MongoDB" ...       }, ...       { ...          Name:"Chris", ...          Subject:"Java" ...       }, ...       { ...   ... Read More

Let us see an example and create a collection with documents −> db.demo557.insertOne({Name:"Chris"});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f28e954b4472ed3e8e864") } > db.demo557.insertOne({Name:"David"});{    "acknowledged" : true, "insertedId" : ObjectId("5e8f28ee54b4472ed3e8e865") }Display all documents from a collection with the help of find() method −> db.demo557.find();This will produce the following output −{ "_id" : ObjectId("5e8f28e954b4472ed3e8e864"), "Name" : "Chris" } { "_id" : ObjectId("5e8f28ee54b4472ed3e8e865"), "Name" : "David" }Following is the query to update only a specific field value −> db.getCollection('demo557').update({Name:"Chris"}, {$set:{Name:"Robert"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Display all documents from a collection with the help of find() method ... Read More

To fetch records from a subdocument array, use $unwind along with $push. For ids beginning from 234, use regex in MongoDB.Let us create a collection with documents −> db.demo556.insertOne( ... { ...    _id:101, ...    details:[ ...       { ...          id:"234336", ...          Name:"Chris" ...       }, ...       { ...          id:"123456", ...          Name:"Bob" ...       }, ...       { ...          id:"234987", ...          Name:"Carol" ...   ... Read More