It is better practice to move all data access code in a data access layer. So simply put this code in a separate class that you could reference and call from your controller. For example you could define an interface that will define the different operations:
public interface IRepository
{
void Insert(SignUpModel model);
}
and then have a specific implementation that is working with the data access technology you are using (EF for example):
public class RepositoryEF : IRepository
{
public void Insert(SignUpModel model)
{
using(DataClassesDataContext dc= new DataClassesDataContext())
{
Dummytable dm = new Dummytable();
dm.Name = sm.password;
}
}
}
and the next step is to have your controller take this repository as constructor dependency:
public class SomeController : Controller
{
private readonly IRepository repo;
public SomeController(IRepository repo)
{
this.repo = repo;
}
[HttpPost]
public ActionResult Index(SignUpModel sm)
{
this.repo.Insert(sm);
...
}
}
Now all that's left is pick up some DI framework and wire up the dependencies.
This way you have a clear separation between your controller logic and the data access layer. This would allow you to unit test the various layers of your application in separation.