// Entity Framework Extensions

// Doc: https://entityframework-extensions.net/allow-duplicate-keys

​

// @nuget: Microsoft.EntityFrameworkCore.SqlServer

// @nuget: Z.EntityFramework.Extensions.EFCore

​

using System;

using System.Linq;

using Microsoft.EntityFrameworkCore;

using System.Collections.Generic;

using Microsoft.Data.SqlClient;

using System.ComponentModel.DataAnnotations;

using System.ComponentModel.DataAnnotations.Schema;

​

public class Program

{

    public static void Main()

    {

        using (var context = new EntityContext())

        {

            context.Database.EnsureCreated();

        }

        GenerateData();

        var list = new List<Customer>() 

        {

            new Customer () { Name = "Customer_A", Description = "Description_updated_1" },

            new Customer () { Name = "Customer_A", Description = "Description_updated_2" },

            new Customer() { Name ="Customer_B", Description = "Description"}   

        };

        // AllowDuplicateKeys: Gets or sets if a duplicate key is possible in the source.

        using (var context = new EntityContext())

        {

            context.BulkMerge(list,options => 

            {

                options.ColumnPrimaryKeyExpression = customer => customer.Name;

                options.AllowDuplicateKeys = true;

            });

​

            FiddleHelper.WriteTable(context.Customers.ToList());

        }

    }

    public static void GenerateData()

    {

        using (var context = new EntityContext())

        {

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

            context.BulkSaveChanges();  

        }

        using (var context = new EntityContext())

        {

            FiddleHelper.WriteTable(context.Customers.ToList());    

        }

    }

    public class EntityContext : DbContext

    {

        public EntityContext() 

        {

        }

​

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)

        {

            optionsBuilder.UseSqlServer(new SqlConnection(FiddleHelper.GetConnectionStringSqlServer()));

​

            base.OnConfiguring(optionsBuilder);

        }

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

    }

    public class Customer

    {

        public int CustomerID { get; set; }

        public string Name { get; set; }

        public string Description { get; set; }

    }

}