LINQ: Handling Of Array, List Object And GROUP BY

Language Integrated Query: LINQ

LINQ introduced in .NET 3.5, mainly used for Query IN Memory and other source of collection and objects.

LINQ having the following different flavour:

1. LINQ To SQL
2. LINQ To XML
3. LINQ To DataSet
4. LINQ To Entities
5. LINQ To Object

With help of LINQ, traditional 6 lines comes down to 1 line, LINQ very. Basically, LINQ is a collection of extensions methods and declared in static classes.

Advantages

1. Reduces the total lines of code.
2. Writing the code very fast and with improved IntelliSense.
3. Compile time type checking of objects.
4. Very fast transformation of One DataType to Another DataType.

We can write LINQ query on the following basis:

1. Query Syntax : Query type style.
2. Method (Lambda) Syntax : Query in Lambda style.

Through the view of LINQ code, you will come to know the benefits of LINQ.

In this article, I have explained how to handle data of Array and List objects.

To do the practice of the following code, please create console application.

_friends is collection of array records, where I filtered PLACE=MUMBAI records.

Example

Friend[] MumbaiFriends = (_friends.Where(x => x.Place == "Mumbai").ToArray());

_friends is collection of array records, where I GroupBy on PLACE records.

Example:

var PlaceGroupData = (_friends.GroupBy(s => s.Place).ToArray());
_friendsList is collection of LIST records, where I filtered PLACE=JODHPUR records.
var JodhpurFriends = (_friendsList.Where(x => x.Place == "Jodhpur").ToList<Friend>());

CONSOLE APPLICATION CODE

 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace LinqIntro
{
    class Program
    {
        static void Main(string[] args)
      {
            Friend[] _friends =
              {
                new Friend
                {
                    FriendID = 1, FriendName = "Rajesh", MobileNumber = "982111111", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 2, FriendName = "Mahesh", MobileNumber = "982122222", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 3, FriendName = "Suresh", MobileNumber = "982133333", Place = "Mumbai", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 4, FriendName = "Jayesh", MobileNumber = "982144444", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 5, FriendName = "Pritesh", MobileNumber = "98115555", Place = "Jodhpur", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 6, FriendName = "Mayuresh", MobileNumber = "98116666", Place = "Jodhpur", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 7, FriendName = "Tarunesh", MobileNumber = "981177777", Place = "Jodhpur", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 8, FriendName = "Ramesh", MobileNumber = "981188888", Place = "Phalodi", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 9, FriendName = "Kamlesh", MobileNumber = "981199999", Place = "Phalodi", Technology = ".NET"
                }
            };

            // Filter the RecordSet
            Friend[] MumbaiFriends = (_friends.Where(x => x.Place == "Mumbai").ToArray());

            Console.WriteLine("Aaray Working Example");
            Console.WriteLine("=====================");
            Console.WriteLine("Printing Mumbai Friends.");
            foreach(Friend frnd in MumbaiFriends)
            {
                Console.WriteLine(frnd.FriendID.ToString() + " " + frnd.FriendName + " " + frnd.Place + " " + frnd.Technology);
            }
            Console.ReadKey();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine("Printing DOT NET Technology Friends.");

            Friend[] DotNetFriends = (_friends.Where(x => x.Technology == ".NET").ToArray());

            foreach(Friend frnd in DotNetFriends) {
                Console.WriteLine(frnd.FriendID.ToString() + " " + frnd.FriendName + " " + frnd.Place + " " + frnd.Technology);
            }
            Console.ReadKey();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();
            // Place Group By
            var PlaceGroupData = (_friends.GroupBy(s => s.Place).ToArray());
            Console.WriteLine("Place ----- Nos. of Friends");
            foreach(var Place in PlaceGroupData)
            {
                Console.WriteLine(Place.Key.ToString() + " ----- " + Place.Count().ToString());
            }
            Console.ReadKey();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();

            //
            Console.WriteLine("List Working Example");
            Console.WriteLine("=====================");
            List < Friend > _friendsList = new List < Friend > ()
            {
                new Friend
                {
                    FriendID = 1, FriendName = "Rajesh", MobileNumber = "982111111", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 2, FriendName = "Mahesh", MobileNumber = "982122222", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 3, FriendName = "Suresh", MobileNumber = "982133333", Place = "Mumbai", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 4, FriendName = "Jayesh", MobileNumber = "982144444", Place = "Mumbai", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 5, FriendName = "Pritesh", MobileNumber = "98115555", Place = "Jodhpur", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 6, FriendName = "Mayuresh", MobileNumber = "98116666", Place = "Jodhpur", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 7, FriendName = "Tarunesh", MobileNumber = "981177777", Place = "Jodhpur", Technology = ".NET"
                },
                new Friend
                {
                    FriendID = 8, FriendName = "Ramesh", MobileNumber = "981188888", Place = "Phalodi", Technology = "JAVA"
                },
                new Friend
                {
                    FriendID = 9, FriendName = "Kamlesh", MobileNumber = "981199999", Place = "Phalodi", Technology = ".NET"
                }
            };

            // Filter the RecordSet
            var JodhpurFriends = (_friendsList.Where(x => x.Place == "Jodhpur").ToList < Friend > ());
            Console.WriteLine("Printing Jodhpur Friends.");
            foreach(Friend frnd in JodhpurFriends)
            {
                Console.WriteLine(frnd.FriendID.ToString() + " " + frnd.FriendName + " " + frnd.Place + " " + frnd.Technology);
            }
            Console.ReadKey();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine("Printing DOT NET Technology Friends.");

            var JavaFriends = (_friends.Where(x => x.Technology == "JAVA").ToList < Friend > ());

            foreach(Friend frnd in JavaFriends)
            {
                Console.WriteLine(frnd.FriendID.ToString() + " " + frnd.FriendName + " " + frnd.Place + " " + frnd.Technology);
            }
            Console.ReadKey();
            Console.WriteLine();

        }
    }

    public class Friend
    {
        public int FriendID
      {
            get;
            set;
        }
        public string FriendName
        {
            get;
            set;
        }
        public string MobileNumber
        {
            get;
            set;
        }
        public string Place
        {
            get;
            set;
        }
        public string Technology
        {
            get;
            set;
        }
    }

}