автоматично створена проміжкова таблиця

different filest.cs

AppDbContext.cs:

using EFCoreCodeFirst.Models;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;

namespace EFCoreCodeFirst
{
    public class AppDbContext : DbContext
    {
        public DbSet<User>? Users => Set<User>();
        public DbSet<Order>? Orders => Set<Order>();

        public DbSet<Product>? Products => Set<Product>();
        public DbSet<Category>? Categories => Set<Category>();

        public DbSet<Person>? People { get; set; }
        public DbSet<Hobby>? Hobbies { get; set; }
        // !!! проміжковий датасет видалено!
  
        public AppDbContext()
        {

        }

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            if (!optionsBuilder.IsConfigured)
            {
                var configuration = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json")
                    .Build();

                optionsBuilder.UseSqlServer(configuration.GetConnectionString("DefaultConnection"));
            }
        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);

            // автоматичне створення проміжкової таблиці для Many-to-Many !!!
            modelBuilder.Entity<Person>()
                .HasMany(p => p.Hobbies)
                .WithMany(h => h.People)
                .UsingEntity(j => j.ToTable("PersonHobbies"));
        }
    }
}

======================================================================================================================

Person.cs:

namespace EFCoreCodeFirst.Models
{
    public class Person
    {
        public int PersonId { get; set; } // PK
        public string? Name { get; set; }

        public ICollection<Hobby> Hobbies { get; set; } = new List<Hobby>(); // Many-to-Many !!!
    }
}

======================================================================================================================

Hobby.cs:

namespace EFCoreCodeFirst.Models
{
    public class Hobby
    {
        public int HobbyId { get; set; } // PK
        public string? Name { get; set; }

        public ICollection<Person> People { get; set; } = new List<Person>(); // Many-to-Many !!!
    }
}

======================================================================================================================

Program.cs: !!!

using EFCoreCodeFirst.Models;
using Microsoft.EntityFrameworkCore;

namespace EFCoreCodeFirst
{
    class Program
    {
        static async Task Main()
        {
            Console.Title = "Міграції";
            Console.OutputEncoding = System.Text.Encoding.UTF8;

            await using var db = new AppDbContext();

            Console.WriteLine("Перевірка та застосування міграцій...");
            await db.Database.MigrateAsync();
            Console.WriteLine("Міграції застосовані (або вже були актуальні).\n");

            var hobby1 = new Hobby { Name = "Футбол" };
            var hobby2 = new Hobby { Name = "Програмування" };
            var hobby3 = new Hobby { Name = "Читання" };
            var hobby4 = new Hobby { Name = "Шахи" };
            var hobby5 = new Hobby { Name = "Спорт" };

            var person1 = new Person { Name = "Олександр", Hobbies = new List<Hobby> { hobby1, hobby3 } };
            var person2 = new Person { Name = "Руслан", Hobbies = new List<Hobby> { hobby2, hobby4 } };
            var person3 = new Person { Name = "Максим", Hobbies = new List<Hobby> { hobby5, hobby1 } };
            var person4 = new Person { Name = "Карина", Hobbies = new List<Hobby> { hobby2, hobby5 } };
            var person5 = new Person { Name = "Аліса", Hobbies = new List<Hobby> { hobby3, hobby4 } };

            db.AddRange(person1, person2, person3, person4, person5);
            db.SaveChanges();


            using (var context = new AppDbContext())
            {
                var peopleWithHobbies = context.People?.Include(p => p.Hobbies).ToList();

                foreach (var person in peopleWithHobbies!)
                {
                    Console.WriteLine($"{person.Name}");
                    foreach (var hobby in person.Hobbies)
                    {
                        Console.WriteLine($" - Захоплення: {hobby.Name}");
                    }
                }
            }
        }
    }
}