// Entity Framework Classic

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

​

// @nuget: Z.EntityFramework.Classic

​

using System;

using System.Collections.Generic;

using System.Linq;

using System.Data.Entity;

public class Program

{

    public static void Main()

    {

        GenerateCustomers(3);

​

        var customers = new List<Customer>();

        for(int i = 0; i < 2; i++)

        {

            // existing customer

            customers.Add(new Customer() { Code = "Code_" + i, FirstName = "Updated_FirstName_" + i, LastName = "Updated_LastName_" + i, NotUpdated = "NotUpdated_" + i });

        }

        for(int i = 1000; i < 1002; i++)

        {

            // new customer

            customers.Add(new Customer() { Code = "Code_" + i, FirstName = "New_FirstName_" + i, LastName = "New_LastName_" + i, NotUpdated = "NotUpdated_" + i });

        }

​

        using(var context = new EntityContext())

        {

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

            context.BulkMerge(customers, options => { 

                options.ColumnInputExpression = customer => new { customer.FirstName, customer.LastName };

                options.ColumnPrimaryKeyExpression = customer => customer.Code;

            });

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

        }

    }

    public static List<Customer> GenerateCustomers(int count)

    {

        var list = new List<Customer>();

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

        {

            list.Add(new Customer() { Code = "Code_" + i, FirstName = "FirstName_" + i, LastName = "LastName_" + i, NotUpdated = "NotUpdated_" + i });

        }

        using (var context = new EntityContext())

        {

            context.BulkInsert(list);

        }

        return list;

    }

​

    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 FirstName { get; set; }

        public string LastName { get; set; }

        public string NotUpdated { get; set; }

    }

}