Casting exception with Entity framework and abstract class

Question

I´m new in entity framework. I´m using EF6 with VS2013.

I need to implement a database from "code-first" approach. The problem is that i´m using an abstract class and i can´t understand why the next pice of code doesn´t work:

public abstract class AClaseT1
{
    //private int idT1;
    [Key]
    public int idT1
    { get; set; }

}

public class ClaseT1Dev1:AClaseT1
{
    //private int dataT1;
    public int dataT1
    { get; set; }
}

public class Contexto : DbContext
{
    public DbSet<AClaseT1> tipos1 { get; set; }        
}

class Program
{
    static void Main(string[] args)
    {

        Database.SetInitializer(new MigrateDatabaseToLatestVersion<Contexto, Configuration>());

        using(var db = new Contexto())
        {
            Console.WriteLine("Int for Tipo1:");
            int d = Console.Read();

            ClaseT1Dev1 t1 = new ClaseT1Dev1() { dataT1 = d };
            db.tipos1.Add(t1);
            db.SaveChanges();

            ClaseT1Dev1 query = (ClaseT1Dev1)from t in db.tipos1
                                            select t;

            Console.WriteLine("Int obtenido de Tipo1 metido en BDD: {0}", query.idT1);
            Console.Read();

        }


    }

When i run the app, it breaks at the "query" line, because it can´t make the casting... Is there a way to make it works? I need a table feeded with different derived objects from the base abstract class (i think it is a TPC inheritance approach).

Thanks for your help!!!

EDIT:

The exact exception thrown at the "query" line is:

InvalidCastException was unhandled

An unhandled exception of type 'System.InvalidCastException' occurred in PruebaCodeFirstDB.exe

Additional information: It is not possible to convert an object of type 'System.Data.Entity.Infrastructure.DbQuery`1[PruebaCodeFirstDB.AClaseT1]' to type 'PruebaCodeFirstDB.ClaseT1Dev1'.

Answer 1

from t in db.tipos1 select t will give you an IEnumerable. You need to change it so that it just returns the one you want