Let us create a collection with documents −> db.demo136.insertOne( ...    { ... ...       "Name":"Chris", ...       "Details":[ ...          { ...             "Id":"101", ...             "EmployeeName":"Mike", ...             "EmployeeDetails":[ ...             { ...                "EmpId":1001, ...                "Salary":1000 ...             }, ...             { ...         ... Read More

To update, use $set along with UPDATE. Let us create a collection with documents −>db.demo135.insertOne({"Details":[{"EmployeeId":101, "EmployeeName":"Chris", "EmployeeSalary":45000}, {"EmployeeId":102, "EmployeeName":"Chris", "EmployeeSalary":45000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31a5ddfdf09dd6d085399c") }Display all documents from a collection with the help of find() method −> db.demo135.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e31a5ddfdf09dd6d085399c"),    "Details" : [       {          "EmployeeId" : 101,          "EmployeeName" : "Chris",          "EmployeeSalary" : 45000       },       {          "EmployeeId" : 102,       ... Read More

To update, use update() along with $set. Let us create a collection with documents −>db.demo134.insertOne({"EmployeeId":101, "EmployeeDetails":[{"EmployeeName":"Chris", "EmployeeAge":27}, {"EmployeeName":"Bob", "EmployeeAge":28}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e319b2f68e7f832db1a7f7c") } >db.demo134.insertOne({"EmployeeId":102, "EmployeeDetails":[{"EmployeeName":"David", "EmployeeAge":24}, {"EmployeeName":"Carol", "EmployeeAge":29}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e319b4468e7f832db1a7f7d") }Display all documents from a collection with the help of find() method −> db.demo134.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e319b2f68e7f832db1a7f7c"),    "EmployeeId" : 101,    "EmployeeDetails" : [       {          "EmployeeName" : "Chris",          "EmployeeAge" : 27       },       ... Read More

To group, use $week and $month in MongoDB. Let us create a collection with documents −> db.demo133.insertOne({"Rank":18, "DueDate":new ISODate("2020-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31980968e7f832db1a7f78") } > db.demo133.insertOne({"Rank":12, "DueDate":new ISODate("2020-01-10")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31982568e7f832db1a7f79") } > db.demo133.insertOne({"Rank":12, "DueDate":new ISODate("2020-02-01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31986568e7f832db1a7f7a") } > db.demo133.insertOne({"Rank":20, "DueDate":new ISODate("2020-02-01")}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31986c68e7f832db1a7f7b") }Display all documents from a collection with the help of find() method −> db.demo133.find();This will produce the following output −{ "_id" : ObjectId("5e31980968e7f832db1a7f78"), "Rank" : 18, "DueDate" : ISODate("2020-01-10T00:00:00Z") } ... Read More

To group across two columns, use $lookup. Let us create a collection with documents −> db.demo132.insertOne({"CountryName1":"US", "CountryName2":"UK", Value:50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31950468e7f832db1a7f75") } > db.demo132.insertOne({"CountryName1":"UK", "CountryName2":"AUS", Value:10}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31951d68e7f832db1a7f76") } > db.demo132.insertOne({"CountryName1":"AUS", "CountryName2":"US", Value:40}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e31952c68e7f832db1a7f77") }Display all documents from a collection with the help of find() method −> db.demo132.find();This will produce the following output −{ "_id" : ObjectId("5e31950468e7f832db1a7f75"), "CountryName1" : "US", "CountryName2" : "UK", "Value" : 50 } { "_id" : ObjectId("5e31951d68e7f832db1a7f76"), "CountryName1" : "UK", "CountryName2" : "AUS", "Value" : ... Read More

For this, use aggregate() in MongoDB. Let us first create a collection with documents −> db.demo131.insertOne( ...    { ...       "_id": 101, ...       "Details": [ ...          { ...             "PlayerScore": 500, ...             "PlayerName": "Chris" ...          }, ...          { ...             "PlayerScore": 400, ...             "PlayerName": "David" ...          } ...       ] ...    } ... ... Read More

Let us first create a collection with documents −> db.demo130.insertOne( ...    { ... ...       "PlayerDetails":[{Score:56}, {Score:78}, {Score:89}, {Score:97}] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3065bf68e7f832db1a7f6d") } > db.demo130.insertOne( ... { ... ...    "PlayerDetails":[{Score:45}, {Score:56}] ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3065c068e7f832db1a7f6e") }Display all documents from a collection with the help of find() method −> db.demo130.find();This will produce the following output −{ "_id" : ObjectId("5e3065bf68e7f832db1a7f6d"), "PlayerDetails" : [ { "Score" : 56 }, { "Score" : 78 }, { "Score" : 89 }, ... Read More

To get distinct first words in a string, use split(). Let us first create a collection with documents −> db.demo129.insertOne({"Words":"This is the MySQL", "CountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e305d6368e7f832db1a7f6b") } > db.demo129.insertOne({"Words":"MongoDB is NOSQL database", "CountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e305d7b68e7f832db1a7f6c") }Display all documents from a collection with the help of find() method −> db.demo129.find();This will produce the following output −{ "_id" : ObjectId("5e305d6368e7f832db1a7f6b"), "Words" : "This is the MySQL", "CountryName" : "US" } { "_id" : ObjectId("5e305d7b68e7f832db1a7f6c"), "Words" : "MongoDB is NOSQL database", "CountryName" : "US" }Following is the query to ... Read More

To get distinct values from a column, use distinct() in MongoDB. Let us first create a collection with documents −> db.demo128.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e30583d68e7f832db1a7f5d") } > db.demo128.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e30584068e7f832db1a7f5e") } > db.demo128.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e30584368e7f832db1a7f5f") } > db.demo128.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e30584668e7f832db1a7f60") } > db.demo128.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e30584c68e7f832db1a7f61") }Display all documents from a collection with the help of find() method −> db.demo128.find();This will produce the following output −{ "_id" : ... Read More

For this, use aggregate() in MongoDB. Let us first create a collection with documents −> db.demo126.insertOne( ...    { ...       "StudentDetails" : { ...          "Number" : 1, ...          "OtherDetails" : [ ...          { ...                "Name" : "Chris", ...                "Score" : 55 ... ...          } ...    ].. }} ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e304b3068e7f832db1a7f56") } > > > db.demo126.insertOne( ...    { ... Read More