To get the data of the nested JSON object in MongoDB, use findOne(). Let us create a collection with documents −> db.demo109.insertOne( ...    { ...       "Name" : "Chris", ...       "Subjects" : [ ...          { ...             "Id" : "100", ...             "Name":"MySQL", ...             "InstructorDetails" : [ ...                { ...                   "Name" : "John" ...         ... Read More

To remove duplicate entries by two keys, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo108.insertOne({"Value1":23, "Value2":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee3e49fd5fd66da214477") } > db.demo108.insertOne({"Value1":23, "Value2":25}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee3f29fd5fd66da214478") } > db.demo108.insertOne({"Value1":23, "Value2":24}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee3f59fd5fd66da214479") }Display all documents from a collection with the help of find() method −> db.demo108.find();This will produce the following output −{ "_id" : ObjectId("5e2ee3e49fd5fd66da214477"), "Value1" : 23, "Value2" : 24 } { "_id" : ObjectId("5e2ee3f29fd5fd66da214478"), "Value1" : 23, "Value2" : 25 } { "_id" : ... Read More

To use variables, work with var in MongoDB. Let us create a collection with documents −> db.demo107.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee1b19fd5fd66da214471") } > db.demo107.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee1b49fd5fd66da214472") } > db.demo107.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ee1b89fd5fd66da214473") }Display all documents from a collection with the help of find() method −> db.demo107.find();This will produce the following output −{ "_id" : ObjectId("5e2ee1b19fd5fd66da214471"), "Name" : "Chris" } { "_id" : ObjectId("5e2ee1b49fd5fd66da214472"), "Name" : "Bob" } { "_id" : ObjectId("5e2ee1b89fd5fd66da214473"), "Name" : "David" }Following is the query to use variable in ... Read More

You can use bulkWrite(). Let us create a collection with documents −> db.demo105.insertOne( { _id:'101', Name:'Chris', Details:[{ Marks1:60, Marks2:70, Marks3:70 }, { Marks1:70, Marks2:70, Marks3:90 }] } ); { "acknowledged" : true, "insertedId" : "101" }Display all documents from a collection with the help of find() method −> db.demo105.find().pretty();This will produce the following output −{    "_id" : "101",    "Name" : "Chris",    "Details" : [       {          "Marks1" : 60,          "Marks2" : 70,          "Marks3" : 70       },       { ... Read More

To implement $dateToString on array items, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo104.insertOne( ...    { ... ...       "AppName" : "Online Book", ...       "Details" : [ ...          { ...             "ClientName" : "Chris", ...             "Deadline" : new ISODate("2020-03-10") ...          } ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ed7fd9fd5fd66da21446f") }Display all documents from a collection with the help of ... Read More

To query on the last object of an array, use aggregate(). Let us create a collection with documents −> db.demo103.insertOne( { "Details" : [    { "StudentId" : 101, "Details" : "MongoDB" },    {"StudentId" : 102, "Details" : "MySQL" },    { "StudentId" : 103, "Details" : "Java" } ], "Details1" : [ { "StudentId" : 104, "Number" : 3 } ] } ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2ed2dd9fd5fd66da21446e") }Display all documents from a collection with the help of find() method −> db.demo103.find();This will produce the following output −{ "_id" : ObjectId("5e2ed2dd9fd5fd66da21446e"), "Details" : ... Read More

For this, create two collections and add some document. After that, use $lookup for match. Let us create a collection with documents −> db.demo101.insertOne( ... { "_id" : "1", "Details" : [ { "PId" : "200" }, { "PId" : "201" }, { "PId" : "201" } ] } ... ) { "acknowledged" : true, "insertedId" : "1" }Display all documents from a collection with the help of find() method −> db.demo101.find();This will produce the following output −{ "_id" : "1", "Details" : [ { "PId" : "200" }, { "PId" : "201" }, { "PId" : "201" } ] ... Read More

To fetch documents except a specific document, set the document to be missed using the $nor in MongoDB. Let us create a collection with documents −> db.demo100.insertOne({"Name":"Chris", "Age":21}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2d9624b8903cdd865577c0") } > db.demo100.insertOne({"Name":"David", "Age":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2d962cb8903cdd865577c1") } > db.demo100.insertOne({"Name":"Bob", "Age":19}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2d9634b8903cdd865577c2") }Display all documents from a collection with the help of find() method −> db.demo100.find();This will produce the following output −{ "_id" : ObjectId("5e2d9624b8903cdd865577c0"), "Name" : "Chris", "Age" : 21 } { "_id" : ObjectId("5e2d962cb8903cdd865577c1"), "Name" : "David", ... Read More

At first, let us create a collection with documents −> db.demo99.insertOne( ...    { ... ...       'Details': ...       { ...          'X': ...          { ...          'Values': [10, 30, 50], ...          'Number':3, ...          }, ...          'Y': ...          { ...             'Values': [1000, 180], ...             'Number': 2, ...          } ...       } ... Read More

To increment a property value of an element, use update() in MongoDB and in that, work with #$inc to increment. Let us first create a collection with documents −> db.demo97.insertOne({ ...    "Details": [ ...       { ...          "Name": "Chris", ...          "Marks": 45 ...       }, ...       { ...          "Name": "Bob", ...          "Marks": 88 ...       }y ...    ] ... } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2d6d24b8903cdd865577af") }Display all ... Read More