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To calculate average, use aggregate along with $avg. Let us first create a collection with documents −> db.calculateAverage.insertOne({'Value':[10, 20, 80]}); { "acknowledged" : true, "insertedId" : ObjectId("5e0383e3f5e889d7a51994dc") } > db.calculateAverage.insertOne({'Value':[12, 15, 16]}); { "acknowledged" : true, "insertedId" : ObjectId("5e0383edf5e889d7a51994dd") } > db.calculateAverage.insertOne({'Value':[30, 35, 40]}); { "acknowledged" : true, "insertedId" : ObjectId("5e0383f5f5e889d7a51994de") }Following is the query to display all documents from a collection with the help of find() method −> db.calculateAverage.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e0383e3f5e889d7a51994dc"), "Value" : [ 10, 20, ... Read More
To promote subfields to top level in projection, use $objectToArray and $arrayToObject. Let us first create a collection with documents:> db.promoteSubfieldsDemo.insertOne({'s':10, 'y':{'t':20, 'u':30, }}); { "acknowledged" : true, "insertedId" : ObjectId("5e038004190a577c668b55d5") }Following is the query to display all documents from a collection with the help of find() method −> db.promoteSubfieldsDemo.find().pretty();This will produce the following output −{ "_id" : ObjectId("5e038004190a577c668b55d5"), "s" : 10, "y" : { "t" : 20, "u" : 30 } }Following is the query to promote subfields to top level in projection without listing all keys ... Read More
To delete specific record, use “$pull” and since we are updating the already created collection, use UPDATE().Let us create a collection with documents −> db.demo213.insertOne({ ... "id": 101, ... "details1": [ ... { ... "Name": "Chris", ... "details2": [ ... { ... "StudentName": "David", ... "Subject": "MongoDB" ... }, ... { ... ... Read More
To find a MongoDB document through a word, use find() and set the word like −word/iLet us create a collection with documents −> db.demo212.insertOne({"details":[{"Name":"John Doe"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3e2c7603d395bdc21346ff") } > db.demo212.insertOne({"details":[{"Name":"Chris Brown"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3e2c8003d395bdc2134700") } > db.demo212.insertOne({"details":[{"Name":"Robert doe"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3e2c8a03d395bdc2134701") }Display all documents from a collection with the help of find() method −> db.demo212.find();This will produce the following output −{ "_id" : ObjectId("5e3e2c7603d395bdc21346ff"), "details" : [ { "Name" : "John Doe" } ] } { "_id" : ObjectId("5e3e2c8003d395bdc2134700"), "details" : ... Read More
To test the values, use $type. Let us create a collection with documents −> db.demo211.insertOne({id:101, "Name":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3e298203d395bdc21346fa") } > db.demo211.insertOne({id:102, "Name":null}); { "acknowledged" : true, "insertedId" : ObjectId("5e3e2a5403d395bdc21346fb") }Display all documents from a collection with the help of find() method −> db.demo211.find();This will produce the following output −{ "_id" : ObjectId("5e3e298203d395bdc21346fa"), "id" : 101, "Name" : "Chris" } { "_id" : ObjectId("5e3e2a5403d395bdc21346fb"), "id" : 102, "Name" : null }Following is the query to test if two external values are equal in a MongoDB criteria object −> v1=200; 200 > v2=200; ... Read More
To get the count of a specific value in MongoDB, use aggregate(). Let us create a collection with documents −> db.demo210.insertOne( ... { ... details: [ ... { ... ClientName: "Robert" ... }, ... { ... ... lientName: "John Doe" ... }, ... { ... ... ClientName: "Robert" ... }, ... { ... ... ... Read More
To convert filed value to create datetime day of month, use MongoDB aggregate(). Let us create a collection with documents −> db.demo209.insertOne( ... { ... "_id" : "101", ... "details" : [ ... { ... "dat" : 1528929908, ... "Name" : "Chris" ... }, ... { ... "dat" : 1529082069, ... "Name":"Carol" ... } ... ], ... ... Read More
To convert numeric string to number, use parseInt() in MongoDB. Let us create a collection with documents −> db.demo208.insertOne( { "value":"50"} ); { "acknowledged" : true, "insertedId" : ObjectId("5e3d92d803d395bdc21346f6") } > db.demo208.insertOne( { "value":"2350"} ); { "acknowledged" : true, "insertedId" : ObjectId("5e3d92dd03d395bdc21346f7") }Display all documents from a collection with the help of find() method −> db.demo208.find();This will produce the following output −{ "_id" : ObjectId("5e3d92d803d395bdc21346f6"), "value" : "50" } { "_id" : ObjectId("5e3d92dd03d395bdc21346f7"), "value" : "2350" }Following is the query to convert numeric string to number −> db.demo208.find().forEach( function (doc) { ... doc.value = parseInt(doc.value); ... Read More
Take the help of $addToSet in MongoDB to specify a return format. Let us create a collection with documents −> db.demo207.insertOne({"FavouriteTechnology":"Spring Boot"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3d8e7a03d395bdc21346f1") } > db.demo207.insertOne({"FavouriteTechnology":"MongoDB"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3d8e8f03d395bdc21346f2") } > db.demo207.insertOne({"FavouriteTechnology":"Groovy"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3d8ea603d395bdc21346f3") }Display all documents from a collection with the help of find() method −> db.demo207.find();This will produce the following output −{ "_id" : ObjectId("5e3d8e7a03d395bdc21346f1"), "FavouriteTechnology" : "Spring Boot" } { "_id" : ObjectId("5e3d8e8f03d395bdc21346f2"), "FavouriteTechnology" : "MongoDB" } { "_id" : ObjectId("5e3d8ea603d395bdc21346f3"), "FavouriteTechnology" : "Groovy" }Following is ... Read More
To determine if a specific value does not exist, use $ne in MongoDB. Let us create a collection with documents −> db.demo206.insertOne( ... { ... "ClientDetails": ... [ ... { ... "Name":"Chris", ... "Age":28, ... "CountryName":"US" ... } ... ] ... } ...); { "acknowledged" : true, "insertedId" : ObjectId("5e3d8bd403d395bdc21346ee") } > db.demo206.insertOne( ... { ... "ClientDetails": ... [ ... ... Read More