using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

     public static void Main(string[] args)

        {

            List<SaleNumber> saleNumbersDK = new List<SaleNumber> {

                new SaleNumber() { VariantId="a",ProductId="A",TotalSales=10 },

                new SaleNumber() { VariantId="b",ProductId="B",TotalSales=20 }

​

            };

            List<SaleNumber> saleNumbersSE = new List<SaleNumber> {

                new SaleNumber() { VariantId="a",ProductId="A",TotalSales=10 },

                new SaleNumber() { VariantId="c",ProductId="c",TotalSales=30 }

​

            };

​

            var innerjoin = saleNumbersDK.Join(saleNumbersSE, d => d.VariantId, s => s.VariantId, (d, s) =>

            {

                return new SaleNumber()

                {

                    VariantId = d.VariantId,

                    ProductId = d.ProductId,

                    TotalSales = d.TotalSales+ (s == null ? 0 : s.TotalSales),

                    TotalSalesDK = d.TotalSales,

                    TotalSalesSE = (d == null ? 0 : d.TotalSales)

                };

            });

            var pendingright= saleNumbersSE.Except(innerjoin, new CustomComparer());

            var pendingleft = saleNumbersDK.Except(innerjoin, new CustomComparer());

            var salesNumber= innerjoin.Concat(pendingright).Concat(pendingleft);

            foreach (var sale in salesNumber)

            {

                Console.WriteLine(sale);

            }

            //Console.ReadLine();

        }

​

}

public class SaleNumber

    {

        public string VariantId { get; set; }

        public string ProductId { get; set; }

        public int TotalSales { get; set; }

        public int TotalSalesDK { get; set; }

        public int TotalSalesSE { get; set; }

​

        public override string ToString()

        {

            return VariantId+"-"+ProductId+"-"+TotalSales+"-"+TotalSalesDK+"-"+TotalSalesSE;

        }

    }

​

public class CustomComparer : IEqualityComparer<SaleNumber>

    {

​

        public bool Equals(SaleNumber x, SaleNumber y)

        {

            return x.VariantId == y.VariantId;

        }

​

        public int GetHashCode(SaleNumber obj)

        {

            return obj.VariantId.GetHashCode();           

        }

    }