The MongoDB aggregation pipeline has stages. Each stage transforms the documents as they pass through the pipeline.Let us first create a collection with documents −> db.demo218.insertOne({"Name":"Chris", "Branch":"CS", Marks:[65, 78, 36, 90]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5f4903d395bdc2134712") } > db.demo218.insertOne({"Name":"David", "Branch":"ME", Marks:[56, 45, 42, 51]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5f6203d395bdc2134713") } > db.demo218.insertOne({"Name":"Chris", "Branch":"CS", Marks:[78, 65, 89]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5f6c03d395bdc2134714") }Display all documents from a collection with the help of find() method −> db.demo218.find();This will produce the following output −{ "_id" : ObjectId("5e3e5f4903d395bdc2134712"), "Name" : "Chris", "Branch" ... Read More

To trim spaces from field, use $trim in MongoDB. Let us create a collection with documents −> db.demo217.insertOne({"FullName":"   Chris Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5d1e03d395bdc213470f") } > db.demo217.insertOne({"FullName":"   David Miller"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5d2503d395bdc2134710") } > db.demo217.insertOne({"FullName":"   John Doe"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e5d2b03d395bdc2134711") }Display all documents from a collection with the help of find() method −> db.demo217.find();This will produce the following output −{ "_id" : ObjectId("5e3e5d1e03d395bdc213470f"), "FullName" : "   Chris Brown" } { "_id" : ObjectId("5e3e5d2503d395bdc2134710"), "FullName" : "   David Miller" ... Read More

Let us first create a collection with documents −> db.demo216.insertOne({"ClientName":"John", "ClientAge":34}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e351003d395bdc213470c") } > db.demo216.insertOne({"ClientName":"Bob", "ClientAge":32}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e351703d395bdc213470d") } > db.demo216.insertOne({"ClientName":"Mike", "ClientAge":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e351c03d395bdc213470e") }Display all documents from a collection with the help of find() method −> db.demo216.find();This will produce the following output −{ "_id" : ObjectId("5e3e351003d395bdc213470c"), "ClientName" : "John", "ClientAge" : 34 } { "_id" : ObjectId("5e3e351703d395bdc213470d"), "ClientName" : "Bob", "ClientAge" : 32 } { "_id" : ObjectId("5e3e351c03d395bdc213470e"), "ClientName" : "Mike", "ClientAge" : 35 }Following is the ... Read More

Since boolean has two values: true and false, therefore, use true or false keyword in MongoDB. Let us create a collection with documents −> db.demo215.insertOne({"EmployeeDetails":[{EmployeeName:"David", "isMarried":false, "Salary":56000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e344003d395bdc2134708") } > db.demo215.insertOne({"EmployeeDetails":[{EmployeeName:"Bob", "isMarried":true, "Salary":60000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e344d03d395bdc2134709") } > db.demo215.insertOne({"EmployeeDetails":[{EmployeeName:"Chris", "isMarried":false, "Salary":78000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e345a03d395bdc213470a") } > db.demo215.insertOne({"EmployeeDetails":[{EmployeeName:"Mike", "isMarried":true, "Salary":17000}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e3e346f03d395bdc213470b") }Display all documents from a collection with the help of find() method −> db.demo215.find();This will produce the following output −{ "_id" ... Read More

To aggregate multiple arrays into a single array, use $project in MongoDB. Let us create a collection with documents −> db.demo119.insertOne( ...    { ...       "_id": 101, ...       "WebDetails": [ ...          { ...             "ImagePath": "/all/image1", ...             "isCorrect": "false" ...          }, ...          { ...             "ImagePath": "/all/image2", ...             "isCorrect": "true" ...          } ...       ... Read More

Let us first create a collection with documents −> db.demo118.insertOne( ...    { ...       "Id" : "101", ...       "Name" : "Chris", ...       "Subjects" : [ ...          "MySQL", ...          "MongoDB", ...          "Java" ...       ], ...       "Details" : [ ...          { ...             "Name" : "David", ...             S:"MongoDB" ...          }, ...          { ... Read More

To aggregate sum of values in a list of dictionaries, use $sum along with aggregate(). Let us create a collection with documents −> db.demo117.insertOne( ...    { ...       ID:101, ...       Details:[ ...          { ...             Name:'Chris', ...             Value1:20, ...             Value2:30, ...             Value3:10 ...          }, ...          { ...             Name:'David', ...         ... Read More

To find only a single document, use findOne() in MongoDB. Let us create a collection with documents −> db.demo116.insertOne({"EmployeeId":101, "EmployeeName":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2eff98d8f64a552dae635b") } > db.demo116.insertOne({"EmployeeId":102, "EmployeeName":"Bob"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2eff9fd8f64a552dae635c") } > db.demo116.insertOne({"EmployeeId":103, "EmployeeName":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2effa5d8f64a552dae635d") } > db.demo116.insertOne({"EmployeeId":102, "EmployeeName":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2effb7d8f64a552dae635e") }Display all documents from a collection with the help of find() method −> db.demo116.find();This will produce the following output −{ "_id" : ObjectId("5e2eff98d8f64a552dae635b"), "EmployeeId" : 101, "EmployeeName" : "John" } { "_id" ... Read More

For this, use find() along with update(). Let us create a collection with documents −> db.demo115.insertOne({"LastName":"Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efe9bd8f64a552dae635a") }Display all documents from a collection with the help of find() method −> db.demo115.find();This will produce the following output −{ "_id" : ObjectId("5e2efe9bd8f64a552dae635a"), "LastName" : "Brown" }Following is the query to update field and modify the data currently in column −> db.demo115.find({"LastName":"Brown"}).forEach(function(d) { ... db.demo115.update({_id: d._id}, {$set: {LastName: 'Hello ' + d.LastName}}); ... })Display all documents from a collection with the help of find() method −> db.demo115.find();This will produce the following output −{ "_id" : ... Read More

To find maximum score, use GROUP() to group documents in a collection. Let us create a collection with documents −> db.demo114.insertOne({"Score":60, "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efc57d8f64a552dae6354") } > db.demo114.insertOne({"Score":87, "Nam+e":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efc5ad8f64a552dae6355") } > db.demo114.insertOne({"Score":45, "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efc5dd8f64a552dae6356") } > db.demo114.insertOne({"Score":67, "Name":"Chris"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efc68d8f64a552dae6357") } > db.demo114.insertOne({"Score":38, "Name":"David"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e2efc74d8f64a552dae6358") }Display all documents from a collection with the help of find() method −> db.demo114.find();This will produce the ... Read More