在ASP.NET Core中实现登录并将数据视为同一张表，可以使用Identity框架来管理用户和角色，并使用Entity Framework Core来操作数据库。

首先，安装必要的NuGet包：

dotnet add package Microsoft.AspNetCore.Identity.EntityFrameworkCore
dotnet add package Microsoft.EntityFrameworkCore.SqlServer

然后，创建一个名为ApplicationUser的自定义用户类，继承自IdentityUser：

using Microsoft.AspNetCore.Identity;

public class ApplicationUser : IdentityUser
{
    // 可以在这里添加额外的用户属性
}

接下来，创建一个名为ApplicationDbContext的自定义数据库上下文类，继承自IdentityDbContext：

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

public class ApplicationDbContext : IdentityDbContext
{
    public ApplicationDbContext(DbContextOptions options)
        : base(options)
    {
    }
}

然后，在Startup.cs文件的ConfigureServices方法中配置Identity和Entity Framework Core：

using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext(options =>
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

    services.AddIdentity()
        .AddEntityFrameworkStores()
        .AddDefaultTokenProviders();

    // 其他服务配置...

    services.AddMvc();
}

接下来，创建一个名为AccountController的控制器，用于处理登录和注册操作：

using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;

public class AccountController : Controller
{
    private readonly SignInManager _signInManager;
    private readonly UserManager _userManager;

    public AccountController(SignInManager signInManager, UserManager userManager)
    {
        _signInManager = signInManager;
        _userManager = userManager;
    }

    [HttpGet]
    public IActionResult Login()
    {
        return View();
    }

    [HttpPost]
    public async Task Login(LoginViewModel model)
    {
        if (ModelState.IsValid)
        {
            var result = await _signInManager.PasswordSignInAsync(model.UserName, model.Password, model.RememberMe, lockoutOnFailure: false);
            if (result.Succeeded)
            {
                return RedirectToAction("Index", "Home");
            }
        }
        ModelState.AddModelError("", "Invalid login attempt");
        return View(model);
    }

    [HttpGet]
    public IActionResult Register()
    {
        return View();
    }

    [HttpPost]
    public async Task Register(RegisterViewModel model)
    {
        if (ModelState.IsValid)
        {
            var user = new ApplicationUser { UserName = model.UserName };
            var result = await _userManager.CreateAsync(user, model.Password);
            if (result.Succeeded)
            {
                await _signInManager.SignInAsync(user, isPersistent: false);
                return RedirectToAction("Index", "Home");
            }
        }
        // 如果出错，将错误添加到ModelState中以在视图中显示
        foreach (var error in result.Errors)
        {
            ModelState.AddModelError("", error.Description);
        }
        return View(model);
    }

    [HttpPost]
    public async Task Logout()
    {
        await _signInManager.SignOutAsync();
        return RedirectToAction("Index", "Home");
    }
}

最后，创建登录和注册的视图文件，例如Login.cshtml和Register.cshtml。

以上是一个基本的登录和注册的解决方案示例，你可以根据具体需求进行修改和扩展。