Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
To search for multiple documents in MongoDB, use $in. Let us create a collection with documents −> db.demo161.insertOne({"ClientId":101, "ClientName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577cafdf09dd6d0853a09") } > db.demo161.insertOne({"ClientId":102, "ClientName":"David"}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577d0fdf09dd6d0853a0a") } > db.demo161.insertOne({"ClientId":103, "ClientName":"David", "ClientAge":35}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577dffdf09dd6d0853a0b") } > db.demo161.insertOne({"ClientId":104, "ClientName":"Carol", "ClientAge":31}); { "acknowledged" : true, "insertedId" : ObjectId("5e3577eefdf09dd6d0853a0c") }Display all documents from a collection with the help of find() method −> db.demo161.find();This will produce the following output −{ "_id" : ObjectId("5e3577cafdf09dd6d0853a09"), "ClientId" : 101, "ClientName" : "Chris" } { ... Read More
To count duplicate date records in MongoDB, use aggregate() and $group. Let us create a collection with documents −> db.demo160.insertOne({"DueDate":new ISODate()}); { "acknowledged" : true, "insertedId" : ObjectId("5e357525fdf09dd6d0853a04") } > db.demo160.insertOne({"DueDate":new ISODate("2019-01-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357532fdf09dd6d0853a05") } > db.demo160.insertOne({"DueDate":new ISODate()}); { "acknowledged" : true, "insertedId" : ObjectId("5e357534fdf09dd6d0853a06") } > db.demo160.insertOne({"DueDate":new ISODate("2019-01-11")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357538fdf09dd6d0853a07") } > db.demo160.insertOne({"DueDate":new ISODate("2020-04-10")}); { "acknowledged" : true, "insertedId" : ObjectId("5e357542fdf09dd6d0853a08") }Display all documents from a collection with the help of find() method −> db.demo160.find();This will produce the following ... Read More
To calculate average value in MongoDB, use aggregate() along with $avg. Let us create a collection with documents −> db.demo159.insertOne({"Score":50}); { "acknowledged" : true, "insertedId" : ObjectId("5e3557b2fdf09dd6d0853a01") } > db.demo159.insertOne({"Score":70}); { "acknowledged" : true, "insertedId" : ObjectId("5e3557b6fdf09dd6d0853a02") } > db.demo159.insertOne({"Score":60}); { "acknowledged" : true, "insertedId" : ObjectId("5e3557c4fdf09dd6d0853a03") }Display all documents from a collection with the help of find() method −> db.demo159.find();This will produce the following output −{ "_id" : ObjectId("5e3557b2fdf09dd6d0853a01"), "Score" : 50 } { "_id" : ObjectId("5e3557b6fdf09dd6d0853a02"), "Score" : 70 } { "_id" : ObjectId("5e3557c4fdf09dd6d0853a03"), "Score" : 60 }Following is the query to ... Read More
To get stats, use explain() in MongoDB. Let us create a collection with documents −> db.demo157.insertOne({"Status":"Active"}); { "acknowledged" : true, "insertedId" : ObjectId("5e354fdffdf09dd6d08539fc") } > db.demo157.insertOne({"Status":"InActive"}); { "acknowledged" : true, "insertedId" : ObjectId("5e354fe3fdf09dd6d08539fd") }Display all documents from a collection with the help of find() method −> db.demo157.find();This will produce the following output −{ "_id" : ObjectId("5e354fdffdf09dd6d08539fc"), "Status" : "Active" } { "_id" : ObjectId("5e354fe3fdf09dd6d08539fd"), "Status" : "InActive" }Following is how to implement explain() in MongoDB −> db.demo157.find({Status: { $in: ['Active', 'InActive'] }}).explain("executionStats");This will produce the following output −{ "queryPlanner" : { "plannerVersion" ... Read More
To sort by difference, use aggregate() in MongoDB. Let us create a collection with documents −> db.demo155.insertOne({"Scores":[{"Value":45}, {"Value":50}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e354584fdf09dd6d08539e3") } > db.demo155.insertOne({"Scores":[{"Value":60}, {"Value":10}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e35458efdf09dd6d08539e4") } > db.demo155.insertOne({"Scores":[{"Value":100}, {"Value":95}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e354599fdf09dd6d08539e5") }Display all documents from a collection with the help of find() method −> db.demo155.find();This will produce the following output −{ "_id" : ObjectId("5e354584fdf09dd6d08539e3"), "Scores" : [ { "Value" : 45 }, { "Value" : 50 } ] } { "_id" : ObjectId("5e35458efdf09dd6d08539e4"), "Scores" : [ { "Value" ... Read More
To query a nested field within an array, use $elemMatch in MongoDB. Let us create a collection with documents −> db.demo153.insertOne({"ClientDetails":[{"ClientName":"Chris", "ClientProject":"Online Banking System"}, {"ClientName":"David", "ClientProject":"Online School Management"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e351957fdf09dd6d08539df") } > db.demo153.insertOne({"ClientDetails":[{"ClientName":"Carol", "ClientProject":"Online Book System"}, {"ClientName":"Mike", "ClientProject":"Game Development"}]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3519c9fdf09dd6d08539e0") }Display all documents from a collection with the help of find() method −> db.demo153.find();This will produce the following output −{ "_id" : ObjectId("5e351957fdf09dd6d08539df"), "ClientDetails" : [ { "ClientName" : "Chris", "ClientProject" : "Online Banking System" }, { "ClientName" ... Read More
To update an array, instead use findAndModify() in MongoDB. Let us create a collection with documents −> db.demo152.insertOne({"id":102, "Name":["Chris", "David"], Score:45}); { "acknowledged" : true, "insertedId" : ObjectId("5e3515bcfdf09dd6d08539dd") } > db.demo152.insertOne({"id":103, "Name":["Mike", "Carol"], Score:65}); { "acknowledged" : true, "insertedId" : ObjectId("5e3515cafdf09dd6d08539de") }Display all documents from a collection with the help of find() method −> db.demo152.find();This will produce the following output −{ "_id" : ObjectId("5e3515bcfdf09dd6d08539dd"), "id" : 102, "Name" : [ "Chris", "David" ], "Score" : 45 } { "_id" : ObjectId("5e3515cafdf09dd6d08539de"), "id" : 103, "Name" : [ "Mike", "Carol" ], "Score" : 65 }Following is the ... Read More
Let us create a collection with documents −> db.demo151.insertOne({"ListOfNames":["Chris", "David", "Mike"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3513b6fdf09dd6d08539da") } > db.demo151.insertOne({"ListOfNames":["Mike", "Bob"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3513c4fdf09dd6d08539db") } > db.demo151.insertOne({"ListOfNames":["John", "David", "Chris"]}); { "acknowledged" : true, "insertedId" : ObjectId("5e3513dcfdf09dd6d08539dc") }Display all documents from a collection with the help of find() method −> db.demo151.find();This will produce the following output −{ "_id" : ObjectId("5e3513b6fdf09dd6d08539da"), "ListOfNames" : [ "Chris", "David", "Mike" ] } { "_id" : ObjectId("5e3513c4fdf09dd6d08539db"), "ListOfNames" : [ "Mike", "Bob" ] } { "_id" : ObjectId("5e3513dcfdf09dd6d08539dc"), "ListOfNames" : [ "John", "David", "Chris" ] ... Read More
For conditional update, use update() and set new value using $set. Let us create a collection with documents −> db.demo150.insertOne({"StudentId":101, "StudentName":"Chris", "StudentMarks":35}); { "acknowledged" : true, "insertedId" : ObjectId("5e350dcdfdf09dd6d08539d3") } > db.demo150.insertOne({"StudentId":102, "StudentName":"Chris", "StudentMarks":55}); { "acknowledged" : true, "insertedId" : ObjectId("5e350dcefdf09dd6d08539d4") } > db.demo150.insertOne({"StudentId":103, "StudentName":"David", "StudentMarks":34}); { "acknowledged" : true, "insertedId" : ObjectId("5e350dcffdf09dd6d08539d5") } > db.demo150.insertOne({"StudentId":104, "StudentName":"Chris", "StudentMarks":38}); { "acknowledged" : true, "insertedId" : ObjectId("5e350dd0fdf09dd6d08539d6") }Display all documents from a collection with the help of find() method −> db.demo150.find();This will produce the following output −{ "_id" : ObjectId("5e350dcdfdf09dd6d08539d3"), "StudentId" : 101, "StudentName" ... Read More
In Java 9, one can retrieve the PID of the process through a native call and can be achievable through the ProcessHandle. We can also retrieve information about the currently running Java Process (JVM) and Info (inner class of ProcessHandle) class that contains details about the process. We can also return a snapshot of all currently running processes in the system.Exampleimport java.lang.ProcessHandle.Info; public class ProcessAPIChanges { public void detailedAPIInfo(ProcessHandle processHandle) { Info processInfo = processHandle.info(); System.out.println("Detailed Process Info is Provided Below: "); System.out.println("[Executable Name] " + processInfo.command().get()); System.out.println("[User Name] " + ... Read More