Let us create a collection with documents −> db.demo411.insertOne( ...    { ...       "Information" : [ ...          { ...             "Name1" : "Chris", ...             "Name2" : "David" ...          }, ...          { ...             "Name1" : "John", ...             "Name2" : "John" ...          } ...       ] ...    } ... ); {    "acknowledged" : true,    "insertedId" ... Read More

To remove elements, use $pull and for such conditions, use $ne. The $ne in MongoDB is used to select the documents where the value of the field is not equal to the specified value.Let us create a collection with documents −> db.demo410.insertOne( ...    { ...       details: [{isMarried:false}, {isMarried:true}, {isMarried:false}, {isMarried:"Chris"}] ...    } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70efc515dc524f70227681") }Display all documents from a collection with the help of find() method −> db.demo410.find();This will produce the following output −{ "_id" : ObjectId("5e70efc515dc524f70227681"), "details" : [ { "isMarried" : false }, { ... Read More

To find documents with a specific string, use find() and in that search for a string with regex. Let us create a collection with documents −> db.demo409.insertOne({"Name":"John Doe"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e4e515dc524f7022767c") } > db.demo409.insertOne({"Name":"Chris Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e4ec15dc524f7022767d") } > db.demo409.insertOne({"Name":"Robert Doe"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e4f415dc524f7022767e") } > db.demo409.insertOne({"Name":"David Brown"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e4fe15dc524f7022767f") }Display all documents from a collection with the help of find() method −> db.demo409.find();This will produce the following output −{ "_id" : ObjectId("5e70e4e515dc524f7022767c"), "Name" ... Read More

To get a query plan in MongoDB, use explain(). The $explain operator gives information on the query plan.Let us create a collection with documents −> db.demo408.insertOne({"Value":50}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e3a115dc524f70227678") } > db.demo408.insertOne({"Value":20}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e3a715dc524f70227679") } > db.demo408.insertOne({"Value":45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e3ac15dc524f7022767a") } > db.demo408.insertOne({"Value":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e70e3af15dc524f7022767b") } > db.demo408.createIndex({Value:1}); {    "createdCollectionAutomatically" : false,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 }Display all documents from a collection with the help ... Read More

To create a new user in MongoDB, use createUser(). Following is the query −> db.createUser( ...    { ...       user: "John", ...       pwd: "123456", ...       roles: [ { role: "readWrite", db: "test" } ], ...       mechanisms: [ "SCRAM-SHA-256" ] ...    } ... )This will produce the following output −Successfully added user: {    "user" : "John",    "roles" : [       {          "role" : "readWrite",          "db" : "test"       }    ],    "mechanisms" : [       "SCRAM-SHA-256"    ] }Following is the query to show all users −> db.getUsers();This will produce the following output −[    {       "_id" : "test.John",       "user" : "John",       "db" : "test",       "roles" : [          {             "role" : "readWrite",             "db" : "test"          }       ],       "mechanisms" : [          "SCRAM-SHA-256"       ]    } ]

For this, use $setIsSubset in MongoDB. Let us create a collection with documents −> db.demo407.insertOne( ...    { ...       Name:"Chris", ...       "details" : [ ...          { ...             id:100 ...          }, ...          { ...             id:110 ...          }, ...          { ...             id:130 ...          } ...       ] ...    } ... ); ... Read More

To aggregate totals, use $sum in MongoDB. Let us create a collection with documents −> db.demo406.insertOne({"Score":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99d5fac4d418a0178599") } > db.demo406.insertOne({"Score":55}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99d8fac4d418a017859a") } > db.demo406.insertOne({"Score":35}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99dcfac4d418a017859b") } > db.demo406.insertOne({"Score":45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99defac4d418a017859c") } > db.demo406.insertOne({"Score":65}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99e3fac4d418a017859d") } > db.demo406.insertOne({"Score":45}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f99e6fac4d418a017859e") }Display all documents from a collection with the help of find() method −> db.demo406.find();This will ... Read More

The find() in MongoDB selects documents in a collection or view and returns a cursor to the selected documents.The find() method with no parameters returns all documents from a collection and returns all fields for the documents. Let us see an example and create a collection with documents −> db.demo405.insertOne({"StudentInfo":{"Name":"Chris"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f9134fac4d418a0178595") } > db.demo405.insertOne({"StudentInfo":{"Name":"David"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f9138fac4d418a0178596") } > db.demo405.insertOne({"StudentInfo":{"Name":"Bob"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f913cfac4d418a0178597") } > db.demo405.insertOne({"StudentInfo":{"Name":"John"}}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f9140fac4d418a0178598") }Display all documents from a ... Read More

Transaction support isn’t available in MongoDB 4.0. To get similar results, use findOneAndUpdate().Let us create a collection with documents −> db.demo404.insertOne({"FirstName":"John"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f8c38fac4d418a0178592") } > db.demo404.insertOne({"FirstName":"Robert"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f8c3cfac4d418a0178593") } > db.demo404.insertOne({"FirstName":"Mike"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e6f8c40fac4d418a0178594") }Display all documents from a collection with the help of find() method −> db.demo404.find();This will produce the following output −{ "_id" : ObjectId("5e6f8c38fac4d418a0178592"), "FirstName" : "John" } { "_id" : ObjectId("5e6f8c3cfac4d418a0178593"), "FirstName" : "Robert" } { "_id" : ObjectId("5e6f8c40fac4d418a0178594"), "FirstName" : "Mike" }Following is the query ... Read More

To sort by words, use $addField along with $cond. Let us create a collection with documents −> db.demo62.insertOne({"Subject":"MySQL"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e287084cfb11e5c34d8992f") } > db.demo62.insertOne({"Subject":"MongoDB"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e287085cfb11e5c34d89930") } > db.demo62.insertOne({"Subject":"Java"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e287086cfb11e5c34d89931") }Display all documents from a collection with the help of find() method −> db.demo62.find();This will produce the following output −{ "_id" : ObjectId("5e287084cfb11e5c34d8992f"), "Subject" : "MySQL" } { "_id" : ObjectId("5e287085cfb11e5c34d89930"), "Subject" : "MongoDB" } { "_id" : ObjectId("5e287086cfb11e5c34d89931"), "Subject" : "Java" }Following is the query to sort by ... Read More