To push a computed expression in $group, use aggregate. Let us first create a collection with documents −> db.demo24.insertOne({"Id":100, "Status":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c58722d07d3b95082e72") } > db.demo24.insertOne({"Id":100, "Status":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c58a22d07d3b95082e73") } > db.demo24.insertOne({"Id":100, "Status":false}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c58f22d07d3b95082e74") } > db.demo24.insertOne({"Id":100, "Status":true}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c59122d07d3b95082e75") } > db.demo24.insertOne({"Id":100, "Status":false}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c59222d07d3b95082e76") }Display all documents from a collection with the help of find() method −> db.demo24.find();This will produce the following output ... Read More

For sub array document in MongoDB, use aggregate along with $sort. Let us first create a collection with documents −> db.demo23.insertOne( ...{ ... ...    "StudentDetails" : [{ ...       "Name" : "David", ...       "Age" : 23, ... ...    }, { ...          "Name" : "Adam", ...          "Age" : 24, ...       }] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e14c3eb22d07d3b95082e71") }Display all documents from a collection with the help of find() method −> db.demo23.find().pretty()This will produce the following ... Read More

To sort values, use sort() in MongoDB. Let us first create a collection with documents −> db.demo365.insertOne({"FirstName":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d5b6d0ada61456dc936f") } > db.demo365.insertOne({"FirstName":"Adam"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d5bad0ada61456dc9370") } > db.demo365.insertOne({"FirstName":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d5bed0ada61456dc9371") } > db.demo365.insertOne({"FirstName":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d5c0d0ada61456dc9372") }Display all documents from a collection with the help of find() method −> db.demo365.find();This will produce the following output −{ "_id" : ObjectId("5e57d5b6d0ada61456dc936f"), "FirstName" : "Chris" } { "_id" : ObjectId("5e57d5bad0ada61456dc9370"), "FirstName" : "Adam" } { "_id" : ... Read More

For this, use $addFields. In that, use the $objectToArray to get the data in the form of keys and values. Use $filter with $indexOfBytes to check if there are any keys with. inside it.Let us first create a collection with documents −> db.demo364.insertOne( ...   { ...       "details" : { ...          "details1.otherdetails.Name" : {"FirstName":"Chris" } ...       } ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d485d0ada61456dc936d") } > db.demo364.insertOne( ...    { ...       "details" : { ...          "details1.otherdetails.Name" ... Read More

The deleteOne() function in MongoDB deletes at most one matching document from a collection. Let us first create a collection with documents −> db.demo363.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d2c3d0ada61456dc9369") } > db.demo363.insertOne({"Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d2c7d0ada61456dc936a") } > db.demo363.insertOne({"Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d2cad0ada61456dc936b") } > db.demo363.insertOne({"Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e57d2d1d0ada61456dc936c") }Display all documents from a collection with the help of find() method −> db.demo363.find();This will produce the following output −{ "_id" : ObjectId("5e57d2c3d0ada61456dc9369"), "Name" : "Chris" } { "_id" : ObjectId("5e57d2c7d0ada61456dc936a"), ... Read More

Let us create a collection with documents −> db.demo362.insertOne({"ClientName":"John", "ClientProject":"School Management System"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a77454a481fef8ec7a1c") } > db.demo362.insertOne({"ClientName":"David", "ClientProject":"Library Management System"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a78454a481fef8ec7a1d") } > db.demo362.insertOne({"ClientName":"Mike", "ClientProject":"Event Tracker"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a7a054a481fef8ec7a1e") } > db.demo362.insertOne({"ClientName":"Carol", "ClientProject":"Hospital Management System"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a7b754a481fef8ec7a1f") }Display all documents from a collection with the help of find() method −> db.demo362.find();This will produce the following output −{ "_id" : ObjectId("5e56a77454a481fef8ec7a1c"), "ClientName" : "John", "ClientProject" : "School Management System" } { "_id" : ... Read More

For finding values, use find() in MongoDB. Under that, use dot notation. Let us create a collection with documents −> db.demo361.insertOne({"details":{"FirstName":"Chris", "LastName":"Brown"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a61f54a481fef8ec7a19") } > db.demo361.insertOne({"details":{"FirstName":"David", "LastName":"Miller"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a62854a481fef8ec7a1a") } > db.demo361.insertOne({"details":{"FirstName":"John", "LastName":"Doe"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a63654a481fef8ec7a1b") }Display all documents from a collection with the help of find() method −> db.demo361.find();This will produce the following output −{ "_id" : ObjectId("5e56a61f54a481fef8ec7a19"), "details" : { "FirstName" : "Chris", "LastName" : "Brown" } } { "_id" : ObjectId("5e56a62854a481fef8ec7a1a"), "details" : { "FirstName" : ... Read More

To get the current and previous documents, use sort(). Since we need only 2 documents, therefore, use LIMIT(2).Let us create a collection with documents −> db.demo360.insertOne({id:101, "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a10c54a481fef8ec7a15") } > db.demo360.insertOne({id:102, "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a11254a481fef8ec7a16") } > db.demo360.insertOne({id:103, "Name":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a11a54a481fef8ec7a17") } > db.demo360.insertOne({id:104, "Name":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e56a11f54a481fef8ec7a18") }Display all documents from a collection with the help of find() method −> db.demo360.find();This will produce the following output −{ "_id" : ObjectId("5e56a10c54a481fef8ec7a15"), "id" : ... Read More

To concatenate in MongoDB, use $concat in $project. Let us create a collection with documents −> db.demo359.insertOne( ...    { ... ...       Name1: "Chris", ...       Name2: "David", ...       Subjects: ["MySQL", "MongoDB", "Java"] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5694cdf8647eb59e5620d0") }Display all documents from a collection with the help of find() method −> db.demo359.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e5694cdf8647eb59e5620d0"),    "Name1" : "Chris",    "Name2" : "David",    "Subjects" : [       "MySQL",       "MongoDB",   ... Read More

Yes, it works in MongoDB. Let us create a collection with documents −> db.demo358.insertOne({"ClientId":101, "ClientName":"Chris", "ClientAge":34}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5692c0f8647eb59e5620cb") } > db.demo358.insertOne({"ClientId":102, "ClientName":"David", "ClientAge":32}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5692caf8647eb59e5620cc") } > db.demo358.insertOne({"ClientId":103, "ClientName":"David", "ClientAge":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5692d2f8647eb59e5620cd") } > db.demo358.insertOne({"ClientId":104, "ClientName":"Bob", "ClientAge":31}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5692ddf8647eb59e5620ce") } > db.demo358.insertOne({"ClientId":105, "ClientName":"Chris", "ClientAge":36}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e5692e7f8647eb59e5620cf") }Display all documents from a collection with the help of find() method −> db.demo358.find();This will produce the following output ... Read More