// Entity Framework Extensions

// Doc: https://entityframework-extensions.net/bulk-merge

​

// @nuget: Z.EntityFramework.Extensions

// @nuget: EntityFramework

​

​

using System.Data.Entity;

using System.Linq;

using System.Text;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        SeedCustomers(2);

        var customers = GenerateCustomers(5);

        using (var context = new EntityContext())

        {

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

            context.BulkMerge(customers, options => {

                options.MergeKeepIdentity = true;

                options.ColumnPrimaryKeyExpression = c => c.Code;

            }); 

​

            FiddleHelper.WriteTable("2 - Customers After", context.Customers.AsNoTracking());

        }   

    }

    public static List<Customer> GenerateCustomers(int count, bool useOld = false) 

    {

        List<Customer>  list = new List<Customer>();

        for(int i = 0; i < count; i++)

        {

            list.Add(new Customer() { CustomerID = 1000 + i, Code = "Code_" + i, Name = (useOld ? "Old_" : "") + "Customer_" + i});

        }

        return list;

    }

    public static void SeedCustomers(int count) 

    {

        var customers = GenerateCustomers(count, true);

        new EntityContext().BulkInsert(customers);

    }

    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 Code { get; set; }

        public string Name { get; set; }

    }

}