private readonly PracticeDevDbContext _context;

public DefaultController(PracticeDevDbContext context)

{

    _context = context;

}

public IActionResult Index()

{

    List<User> newUsers = new List<User>

    {

        new User{ Email = "", Other="w w w w w", UserName="user 2"},

        new User{ Email = "", Other="e e e e e", UserName="user 3"},

        new User{ Email = "", Other="r r r r r", UserName="user 4"},

        new User{ Email = "", Other="t t t t t ", UserName="user 5"},

        new User{ Email = "", Other="y y y y y", UserName="user 6"},

        new User{ Email = "", Other="u u u u u", UserName="user 7"},

    };

    List<User> oldUsers = _context.Users.ToList();

    foreach(var user in newUsers)

    {

        var tempUser = oldUsers.Where(o => o.Email == user.Email).FirstOrDefault();

        if(tempUser != null)

        {

            tempUser.Other = user.Other;

            tempUser.UserName = user.UserName;

            _context.Users.Update(tempUser);

        }

        else

        {

            user.Id = new Random().Next(,);

            _context.Users.Add(user);

        }

    }

    _context.SaveChanges();

    return Content("我的测试");

}