// @nuget: EntityFramework

// @nuget: Z.EntityFramework.Extensions

​

using System;

using System.Collections.Generic;

using System.Linq;

using System.Data.Entity;

​

public class Program

{

    public static void Main()

    {       

        GenerateData();     

​

        using (var context = new EntityContext())

        {

            var list = context.Customers.ToList();

​

            list.ForEach(x => x.Name = "NewName");

            FiddleHelper.WriteTable("1 - Before", context.Customers.AsNoTracking().ToList());

            context.BulkMerge(list, options => {

                options.ColumnMappings.Add(new Z.BulkOperations.ColumnMapping<Customer>(x => x.CustomerID, true));

                options.ColumnMappings.Add(new Z.BulkOperations.ColumnMapping<Customer>(x => x.Name));

                var columnMapping = new Z.BulkOperations.ColumnMapping<Customer>(x => x.Description);

                columnMapping.FormulaUpdate = "DestinationTable.Name + ';' + StagingTable.Description";

                options.ColumnMappings.Add(columnMapping);

            });

            FiddleHelper.WriteTable("1 - After", context.Customers.AsNoTracking().ToList());    

        }

    }

    public static void GenerateData()

    {

        using (var context = new EntityContext())

        {

            context.Customers.Add(new Customer() { Name ="Customer_A", Description = "Description" });

            context.Customers.Add(new Customer() { Name ="Customer_B", Description = "Description"});

​

            context.BulkSaveChanges();  

        }

    }

    public class EntityContext : DbContext

    {

        public EntityContext() : base(FiddleHelper.GetConnectionStringSqlServer())

        {

​

        }

        public DbSet<Customer> Customers { get; set; }

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

    }

}