LINQ - GroupBy

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml;
using System.Xml.Linq;
using System.Data.Sql;
using System.Data;

namespace Linq_Grouping
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Enter your choice. \n1-> Linq With XML\n2->Linq With DataTable\n3-> Linq With Entities");
            int choice = int.Parse(Console.ReadLine());
            if (choice == 1)
                ExecuteLinqWithXML();
            else if (choice == 2)
                ExecuteLinqWithDataTable();
            else if (choice == 3)
                ExecuteLinqWithEntities();
            Console.ReadLine();
        }

        static void ExecuteLinqWithXML()
        {
            Random rnd = new Random();
            XElement Customers = new XElement("Customers");
            for (int i = 0; i < 25; i++)
            {
                Customers.Add(
                    new XElement("Customer",
                        new XElement("Id", ("cust_id" + (i + 1))),
                        new XElement("Name", "Customer" + (i + 1)),
                        new XElement("Category", "Cat" + ((i + 1)) % 6),
                        new XElement("Sales", (rnd.Next(100, 1000)))
                        )
                    );
            }

            var results = from p in Customers.Descendants("Customer")
                          group p by p.Element("Category").Value into grps
                          select new
                          {
                              Key = grps.Key,
                              Values = grps,
                              TotalSales = grps.Sum(g => decimal.Parse(g.Element("Sales").Value)),
                              Total = grps.Count(),
                              AvgSales = grps.Average(g => decimal.Parse(g.Element("Sales").Value)),
                              MaxSales = grps.Max(g => decimal.Parse(g.Element("Sales").Value)),
                              MinSales = grps.Min(g => decimal.Parse(g.Element("Sales").Value))
                          };

            foreach (var result in results)
            {
                Console.WriteLine("Category - " + result.Key);
                Console.WriteLine("Total Sales : " + result.TotalSales + " Average Sales : " + result.AvgSales + " Maximum Sales : " + result.MaxSales + " Minimum Sales : " + result.MinSales);
                Console.WriteLine("ID\t\t\tName\t\t\tCategory\tSales");
                foreach (XElement Customer in result.Values)
                {
                    Console.WriteLine(
                        Customer.Element("Id").Value + "\t\t" +
                        Customer.Element("Name").Value + "\t\t" +
                        Customer.Element("Category").Value + "\t\t" +
                        Customer.Element("Sales").Value + "\t\t"
                        );
                }

            }
        }
        static void ExecuteLinqWithDataTable()
        {
            DataTable dtCustomers = new DataTable("Customers");
            dtCustomers.Columns.Add(new DataColumn("ID", typeof(string)));
            dtCustomers.Columns.Add(new DataColumn("Name", typeof(string)));
            dtCustomers.Columns.Add(new DataColumn("Category", typeof(string)));
            dtCustomers.Columns.Add(new DataColumn("Sales", typeof(decimal)));
            Random rnd = new Random();
            for (int i = 0; i < 25; i++)
            {
                DataRow dr = dtCustomers.NewRow();
                dr["ID"] = "Cust_" + (i + 1);
                dr["Name"] = "Customer-" + (i + 1);
                dr["Category"] = "Cat_" + ((i + 1) % 6);
                dr["Sales"] = rnd.Next(500, 1000);
                dtCustomers.Rows.Add(dr);
            }
            var results = from p in dtCustomers.AsEnumerable()
                          group p by p.Field<string>("Category") into grps
                          select new
                          {
                              Key = grps.Key,
                              Values = grps,
                              TotalSales = grps.Sum(g => g.Field<decimal>("Sales")),
                              Total = grps.Count(),
                              AvgSales = grps.Average(g => g.Field<decimal>("Sales")),
                              MaxSales = grps.Max(g => g.Field<decimal>("Sales")),
                              MinSales = grps.Min(g => g.Field<decimal>("Sales"))
                          };
            foreach (var result in results)
            {
                Console.WriteLine("Category - " + result.Key);
                Console.WriteLine("Total Sales : " + result.TotalSales + " Average Sales : " + result.AvgSales + " Maximum Sales : " + result.MaxSales + " Minimum Sales : " + result.MinSales);
                Console.WriteLine("ID\t\tName\t\t\tCategory\tSales");
                foreach (DataRow Customer in result.Values)
                {
                    Console.WriteLine(
                        Customer["ID"] + "\t\t" +
                        Customer["Name"] + "\t\t" +
                        Customer["Category"] + "\t\t" +
                        Customer["Sales"] + "\t\t"
                        );
                }

            }
        }
        static void ExecuteLinqWithEntities()
        {
            Random rnd = new Random();
            List<Customer> Customers = new List<Customer>();
            for (int i = 0; i < 25; i++)
                Customers.Add(new Customer
                 {
                     ID = "Cust" + (i + 1),
                     Category = "Cat_" + ((i + 1) % 6),
                     Name = "Customer_" + (i + 1),
                     Sales = rnd.Next(500, 1000)
                 });
            var results = from p in Customers
                          group p by p.Category into grps
                          select new
                          {
                              Key = grps.Key,
                              Values = grps,
                              TotalSales = grps.Sum(g => g.Sales),
                              Total = grps.Count(),
                              AvgSales = grps.Average(g => g.Sales),
                              MaxSales = grps.Max(g => g.Sales),
                              MinSales = grps.Min(g => g.Sales),
                          };
            foreach (var result in results)
            {
                Console.WriteLine("Category - " + result.Key);
                Console.WriteLine("Total Sales : " + result.TotalSales + " Average Sales : " + result.AvgSales + " Maximum Sales : " + result.MaxSales + " Minimum Sales : " + result.MinSales);
                Console.WriteLine("ID\t\tName\t\t\tCategory\tSales");
                foreach (Customer Customer in result.Values)
                {
                    Console.WriteLine(
                        Customer.ID + "\t\t" +
                        Customer.Name + "\t\t" +
                        Customer.Category + "\t\t" +
                        Customer.Sales + "\t\t"
                        );
                }

            }

        }
    }


    public class Customer
    {
        public string ID { get; set; }
        public string Name { get; set; }
        public string Category { get; set; }
        public decimal Sales { get; set; }
    }
}