public List <AutoMarca> ObtenerAutosOfertados()
        {
            List <AutoMarca> lista = new List <AutoMarca>();
            SqlConnection    conn  = new SqlConnection(@"Data Source=PABLITO\SQLDESARROLLO;Initial Catalog=Concesionaria;Integrated Security=True;");

            conn.Open();

            SqlCommand comm = conn.CreateCommand();

            comm.CommandText = "select idAuto,patente,nombre,km,promocion,precio from Autos a join Marcas m on a.idMarca=m.idMarca where promocion=1";

            SqlDataReader dr = comm.ExecuteReader();

            while (dr.Read())
            {
                int    idAuto    = dr.GetInt32(0);
                string patente   = dr.GetString(1);
                string marca     = dr.GetString(2);
                int    km        = dr.GetInt32(3);
                bool   promocion = dr.GetBoolean(4);
                float  precio    = dr.GetFloat(5);


                AutoMarca autoM = new AutoMarca(idAuto, patente, marca, km, promocion, precio);
                lista.Add(autoM);
            }
            dr.Close();
            conn.Close();
            return(lista);
        }
        public AutoMarca ObtenerAutoUsado()
        {
            AutoMarca     a    = null;
            SqlConnection conn = new SqlConnection(@"Data Source=PABLITO\SQLDESARROLLO;Initial Catalog=Concesionaria;Integrated Security=True;");

            conn.Open();

            SqlCommand comm = conn.CreateCommand();

            comm.CommandText = "select idAuto,patente,nombre,km,promocion,precio from Autos a join Marcas m on a.idMarca=m.idMarca where km=(select min(km) from Autos);";

            SqlDataReader dr = comm.ExecuteReader();

            if (dr.Read())
            {
                int    idAuto    = dr.GetInt32(0);
                string patente   = dr.GetString(1);
                string marca     = dr.GetString(2);
                int    km        = dr.GetInt32(3);
                bool   promocion = dr.GetBoolean(4);
                float  precio    = dr.GetFloat(5);

                a = new AutoMarca(idAuto, patente, marca, km, promocion, precio);
            }
            dr.Close();
            conn.Close();
            return(a);
        }