static void Main(string[] args)
 {
     // use database
     using (var db = new UserDatabaseContext())
     {
         users      = db.Users.ToList();
         categories = db.Categories.ToList();
     }
     users.ForEach(u => Console.WriteLine($"{u.UserId,-10}"));
 }
        static void Main(string[] args)
        {
            //use database
            using (var db = new UserDatabaseContext())
            {
                db.Database.EnsureDeleted();
                db.Database.EnsureCreated();

                var category1 = new Category()
                {
                    CategoryName = "Admin"
                };
                var category2 = new Category()
                {
                    CategoryName = "User"
                };
                var category3 = new Category()
                {
                    CategoryName = "Personal"
                };
                var user1 = new User()
                {
                    UserName = "******", CategoryId = 1
                };
                var user2 = new User()
                {
                    UserName = "******", CategoryId = 2
                };
                var user3 = new User()
                {
                    UserName = "******", CategoryId = 3
                };

                db.Categories.AddRange(category1, category2, category3);
                db.Users.AddRange(user1, user2, user3);
                db.SaveChanges();

                users      = db.Users.ToList();
                categories = db.Categories.ToList();
            }

            foreach (var item in users)
            {                                                                   //pointer to category
                Console.WriteLine($"{item.UserId,-15} {item.UserName,-15} {item.Category.CategoryName} \n");
            }
            //users.ForEach(u => Console.WriteLine(u.UserName));
            //categories.ForEach(u => Console.WriteLine(u.CategoryName));
        }