To update the nested document, use update() and within that, use dot notation. Let us create a collection with documents −> db.demo607.insertOne( ...    { ...       id:1, ...       "Info1" : { ...          "Name" : "Chris", ...          "Age" : 21, ... ...          "Info2" : { ...             "SubjectName" : "MongoDB", ...             "Marks" : 89 ...          } ...       } ...    } ... ); {   ... Read More

For average in MongoDB, use the $avg. Let us create a collection with documents. Here, we have duplicate ids with rating for each −> db.demo606.insertOne({id:1, rating:5});{    "acknowledged" : true, "insertedId" : ObjectId("5e972dfbf57d0dc0b182d623") } > db.demo606.insertOne({id:1, rating:4});{    "acknowledged" : true, "insertedId" : ObjectId("5e972dfef57d0dc0b182d624") } > db.demo606.insertOne({id:2, rating:3});{    "acknowledged" : true, "insertedId" : ObjectId("5e972e09f57d0dc0b182d625") } > db.demo606.insertOne({id:1, rating:null});{    "acknowledged" : true, "insertedId" : ObjectId("5e972e0ef57d0dc0b182d626") } > db.demo606.insertOne({id:2, rating:null});{    "acknowledged" : true, "insertedId" : ObjectId("5e972e15f57d0dc0b182d627") } > db.demo606.insertOne({id:2, rating:3});{    "acknowledged" : true, "insertedId" : ObjectId("5e972e1bf57d0dc0b182d628") }Display all documents from a collection with the help of find() method ... Read More

For this, use UPDATE() method and within that set the two conditions. Let us create a collection with documents −> db.demo605.insertOne( ...    { ...       _id:1, ...       "Information" : [ ...          { ...             "id" : "Product-1", ...             "Quantity" : 50, ...          }, ...          { ...             "id" : "Product-2", ...             "Quantity" : 100, ...          }, ... Read More

For this, set “unique:true” i.e. the unique constraint and avoid inserting duplicates as in the below syntax −db.yourCollectionName.ensureIndex({yourFieldName: 1}, {unique: true, dropDups: true})To understand the above syntax, let us create a collection with documents. Here, duplicate insertion won’t be allowed −> db.demo604.ensureIndex({FirstName: 1}, {unique: true, dropDups: true});{    "createdCollectionAutomatically" : true,    "numIndexesBefore" : 1,    "numIndexesAfter" : 2,    "ok" : 1 } > db.demo604.insertOne({FirstName:"Chris"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e960887ed011c280a0905d8") } > db.demo604.insertOne({FirstName:"Bob"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e96088aed011c280a0905d9") } > db.demo604.insertOne({FirstName:"David"});{    "acknowledged" : true,    "insertedId" : ObjectId("5e96088ded011c280a0905da") } > db.demo604.insertOne({FirstName:"Chris"}); 2020-04-15T00:31:35.978+0530 ... Read More

The NumberLong(x) goes beyond its limit value and round off the value whereas NumberLong(“x”) does not.Now, we will consider a number and would use it for both NumberLong(x) and NumberLong(“x”) to see the difference.Let us create a collection with documents −> db.demo603.insert({"longValue" : NumberLong(988998985857575789)}); WriteResult({ "nInserted" : 1 }) > db.demo603.insert({"longValueInString" : NumberLong("988998985857575789")});Display all documents from a collection with the help of find() method −> db.demo603.find().pretty();This will produce the following output −{    "_id" : ObjectId("5e9605e5ed011c280a0905d1"),    "longValue" : NumberLong("988998985857575808") } {    "_id" : ObjectId("5e9605faed011c280a0905d2"),    "longValueInString" : NumberLong("988998985857575789") }

For such grouping of documents, use $group in MongoDB aggregate(). Let us create a collection with documents −> db.demo602.insertOne({id:1, Name:"Chris"});{    "acknowledged" : true, "insertedId" : ObjectId("5e960080ed011c280a0905c9") } > db.demo602.insertOne({id:2, Name:"David"});{    "acknowledged" : true, "insertedId" : ObjectId("5e960086ed011c280a0905ca") } > db.demo602.insertOne({id:1, Name:"Bob"});{    "acknowledged" : true, "insertedId" : ObjectId("5e96008ced011c280a0905cb") } > db.demo602.insertOne({id:3, Name:"Mike"});{    "acknowledged" : true, "insertedId" : ObjectId("5e960092ed011c280a0905cc") } > db.demo602.insertOne({id:2, Name:"John"});{    "acknowledged" : true, "insertedId" : ObjectId("5e960099ed011c280a0905cd") } > db.demo602.insertOne({id:1, Name:"Sam"});{    "acknowledged" : true, "insertedId" : ObjectId("5e9600a1ed011c280a0905ce") }Display all documents from a collection with the help of find() method −> db.demo602.find();This will produce the following ... Read More

Let us create a collection with documents −> db.demo601.insertOne( ...    { ...       id:1, ...       userDetails: ...          { ...             userName:"John", ...             userMailId:"John@gmail.com" ...          } ...       } ...    ); {    "acknowledged" : true,    "insertedId" : ObjectId("5e95ff5ced011c280a0905c7") } > > db.demo601.insertOne( { id:2, userDetails: { userName:"Carol", userMailId:"Carol@gmail.com" } } );{    "acknowledged" : true,    "insertedId" : ObjectId("5e95ff71ed011c280a0905c8") }Display all documents from a collection with the help of find() method ... Read More

For this, use userAdminAnyDatabase since it gives all permission like admin. Following is the syntax −use admin db.createUser(    {       user: "yourUserName",       pwd: "yourPassword",       roles: [ { role: "yourRoleName", db: "yourDatabaseName" } ]    } )Let us implement the above syntax to create a user role. Following is the query to create a user with role "userAdminAnyDatabase" −> use admin switched to db admin > db.createUser( ...    { ...       user: "David Miller", ...       pwd: "123456", ...       roles: [ { role: "userAdminAnyDatabase", db: "admin" } ] ...    } ... )This will produce the following output −Successfully added user: {    "user" : "David Miller",    "roles" : [       {          "role" : "userAdminAnyDatabase",          "db" : "admin"       }    ] }

To update, use update() and following is the syntax to create and use a sample custom variable −var anyVariableName=yourValue; db.yourCollectionName.update({filter}, {$set:{yourFieldName:yourVariableName}});Let us create a collection with documents −> db.demo600.insertOne({id:1, Name:"Robert"});{    "acknowledged" : true, "insertedId" : ObjectId("5e94a063f5f1e70e134e2699") } > db.demo600.insertOne({id:2, Name:"Mike"});{    "acknowledged" : true, "insertedId" : ObjectId("5e94a06bf5f1e70e134e269a") } > db.demo600.insertOne({id:3, Name:"Sam"});{    "acknowledged" : true, "insertedId" : ObjectId("5e94a072f5f1e70e134e269b") }Display all documents from a collection with the help of find() method −> db.demo600.find();This will produce the following output −{ "_id" : ObjectId("5e94a063f5f1e70e134e2699"), "id" : 1, "Name" : "Robert" } { "_id" : ObjectId("5e94a06bf5f1e70e134e269a"), "id" : 2, "Name" : "Mike" } ... Read More

To subtract values from document field values, use $subtract in MongoDB aggregate(). Let us create a collection with documents −> db.demo599.insertOne({"TotalPrice":250, "DiscountPrice":35});{    "acknowledged" : true, "insertedId" : ObjectId("5e948192f5f1e70e134e2696") } > db.demo599.insertOne({"TotalPrice":400, "DiscountPrice":10});{    "acknowledged" : true, "insertedId" : ObjectId("5e948199f5f1e70e134e2697") } > db.demo599.insertOne({"TotalPrice":1550, "DiscountPrice":50});{    "acknowledged" : true, "insertedId" : ObjectId("5e9481a0f5f1e70e134e2698") }Display all documents from a collection with the help of find() method −> db.demo599.find();This will produce the following output −{ "_id" : ObjectId("5e948192f5f1e70e134e2696"), "TotalPrice" : 250, "DiscountPrice" : 35 } { "_id" : ObjectId("5e948199f5f1e70e134e2697"), "TotalPrice" : 400, "DiscountPrice" : 10 } { "_id" : ObjectId("5e9481a0f5f1e70e134e2698"), "TotalPrice" : 1550, "DiscountPrice" ... Read More