Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Let us first create a document −> var document= [ ... { "SubjectName" : "MySQL", "Marks" : 78 }, ... { "SubjectName" : "MongoDB", "Marks" : 89 }, ... { "SubjectName" : "Java", "Marks" : 71 }, ... ];Following is the query to display document −> printjson(document);This will produce the following output −[ { "SubjectName" : "MySQL", "Marks" : 78 }, { "SubjectName" : "MongoDB", "Marks" : 89 }, { "SubjectName" : "Java", "Marks" : 71 } ]Following is the query to project grouping into an object in MongoDB −> var makeObject= {}; > document.forEach(function (d){ ... makeObject[d.SubjectName] = d.Marks; ... }); > printjson(makeObject);This will produce the following output −{ "MySQL" : 78, "MongoDB" : 89, "Java" : 71 }
To get an average of array elements, use $avg. Let us create a collection with documents −> db.demo584.insertOne({"Marks":[75,50,85,60,80]});{ "acknowledged" : true, "insertedId" : ObjectId("5e91d827fd2d90c177b5bcc2") }Display all documents from a collection with the help of find() method −> db.demo584.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e91d827fd2d90c177b5bcc2"), "Marks" : [ 75, 50, 85, 60, 80 ] }Following is the query to find avg in the aggregation of array element −> db.demo584.aggregate([ ... { $project: { MarksAvg: { $avg: "$Marks"} } } ... ])This will produce the following output −{ "_id" : ObjectId("5e91d827fd2d90c177b5bcc2"), "MarksAvg" : 70 }
The accumulators are operators that maintain their state as documents progress through the pipeline.The $ROOT references the root document, i.e. the top-level document, currently being processed in the aggregation pipeline stage.Let us create a collection with documents −> db.demo582.insertOne({FirstName:"Chris", Age:21, createDate:new ISODate("2020-01-10")});{ "acknowledged" : true, "insertedId" : ObjectId("5e91ce41fd2d90c177b5bcbd") } > db.demo582.insertOne({FirstName:"Chris", Age:21, createDate:new ISODate("2020-04-21")});{ "acknowledged" : true, "insertedId" : ObjectId("5e91ce4ffd2d90c177b5bcbe") } > db.demo582.insertOne({FirstName:"Chris", Age:22, createDate:new ISODate("2020-02-11")});{ "acknowledged" : true, "insertedId" : ObjectId("5e91ce59fd2d90c177b5bcbf") } > db.demo582.insertOne({FirstName:"Chris", Age:22, createDate:new ISODate("2020-01-12")});{ "acknowledged" : true, "insertedId" : ObjectId("5e91ce6efd2d90c177b5bcc0") }Display all documents from a collection with the help of find() method ... Read More
To order a list, use sort(). Let us create a collection with documents −> db.demo581.insertOne({"Name":"Chris", "Score":56});{ "acknowledged" : true, "insertedId" : ObjectId("5e91cbbbfd2d90c177b5bcb6") } > db.demo581.insertOne({"Name":"Bob", "Score":240});{ "acknowledged" : true, "insertedId" : ObjectId("5e91cbbbfd2d90c177b5bcb7") } > db.demo581.insertOne({"Name":"David", "Score":150});{ "acknowledged" : true, "insertedId" : ObjectId("5e91cbbcfd2d90c177b5bcb8") }Display all documents from a collection with the help of find() method −> db.demo581.find();This will produce the following output −{ "_id" : ObjectId("5e91cbbbfd2d90c177b5bcb6"), "Name" : "Chris", "Score" : 56 } { "_id" : ObjectId("5e91cbbbfd2d90c177b5bcb7"), "Name" : "Bob", "Score" : 240 } { "_id" : ObjectId("5e91cbbcfd2d90c177b5bcb8"), "Name" : "David", "Score" : 150 }Following is the query ... Read More
To calculate the sum of unique properties in different collection elements, use $cond along with $group. This gives the resultant price.Let us create a collection with documents −> db.demo580.insertOne( ... { ... "Name":"John", ... "Id1":"110", ... "Id2":"111", ... "Price":10.5 ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e918cebfd2d90c177b5bcae") } > > db.demo580.insertOne( ... { ... "Name":"John", ... "Id1":"111", ... "Id2":"", ... "Price":9.5 ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5e918cecfd2d90c177b5bcaf") }Display all documents ... Read More
To slice only one element of array, use $slice in MongoDB. Let us create a collection with documents −> db.demo579.insertOne( ... { ... "_id" : 101, ... "details" : { "FirstName" : "John" }, ... "Marks" : [ 56,78,90,34,45,74 ] ... } ... ); { "acknowledged" : true, "insertedId" : 101 }Display all documents from a collection with the help of find() method −> db.demo579.find().pretty();This will produce the following output −{ "_id" : 101, "details" : { "FirstName" : "John" }, "Marks" : [ 56, 78, 90, 34, 45, 74 ] }Following is the query to slice only one the element of the array −> db.demo579.find({},{Marks : {$slice : 1} ,"details":0,"_id":0})This will produce the following output −{ "Marks" : [ 56 ] }
For this, use aggregate() along with $group. Let us create a collection with documents −> db.demo578.insertOne( ... { ... "_id" : 1, ... "Info" : { ... "firstName" : "Chris", ... "lastName" : "Brown" ... }, ... ... "achievements" : [ ... { ... "winner" : "10th", ... "year" : 2010, ... "by" : "School" ... ... Read More
To sort MongoDB collection by Array value, use aggregate() along with $sort. Let us create a collection with documents −> db.demo577.insertOne( ... { ... ... "student": { ... "details": [ ... { ... Name:"Chris", ... Score:45 ... }, ... { ... Name:"Bob", ... Score:33 ... ... Read More
Let us create a collection with documents −> db.demo576.insertOne({id:101, Name:"Chris", Marks:45}){ "acknowledged" : true, "insertedId" : ObjectId("5e916c3b581e9acd78b427fa") } > db.demo576.insertOne({id:101, Name:"John", Marks:55}){ "acknowledged" : true, "insertedId" : ObjectId("5e916c43581e9acd78b427fb") } > db.demo576.insertOne({id:101, Name:"John", Marks:65}){ "acknowledged" : true, "insertedId" : ObjectId("5e916c47581e9acd78b427fc") } > db.demo576.insertOne({id:102, Name:"David", Marks:37}){ "acknowledged" : true, "insertedId" : ObjectId("5e916c55581e9acd78b427fd") } > db.demo576.insertOne({id:102, Name:"David", Marks:75}){ "acknowledged" : true, "insertedId" : ObjectId("5e916c5e581e9acd78b427fe") }Display all documents from a collection with the help of find() method −> db.demo576.find();This will produce the following output −{ "_id" : ObjectId("5e916c3b581e9acd78b427fa"), "id" : 101, "Name" : "Chris", "Marks" : 45 } { ... Read More