public IEnumerable<Movie> GetMoviesDirectedBy(
  string directorName)
{
  var query = from m in _session.Query<Movie>()
              where m.Director == directorName
              select m;
  return query.ToList();
}

public IEnumerable<Movie> GetMoviesWith(
  string actorName)
{
  var query = from m in _session.Query<Movie>()
              where m.Actors.Any(
                ar => ar.Actor == actorName)
              select m;
  return query.ToList();
}

public Book GetBookByISBN(string isbn)
{
  var query = from b in _session.Query<Book>()
              where b.ISBN == isbn
              select b;
  return query.SingleOrDefault();
}

public IEnumerable<Product> GetProductByPrice(
  decimal minPrice,
  decimal maxPrice)
{
  var query = from p in _session.Query<Product>()
              where p.UnitPrice >= minPrice &&
              p.UnitPrice <= maxPrice
              orderby p.UnitPrice ascending 
              select p;

  return query.ToList();
}


public IEnumerable<NameAndPrice> GetMoviePriceList()
{
  var query = from m in _session.Query<Movie>()
              select new NameAndPrice(
                m.Name,
                m.UnitPrice);
  return query.ToList();
}

public decimal GetAverageMoviePrice()
{
  return _session.Query<Movie>()
    .Average(m => m.UnitPrice);
}

public IEnumerable<NameAndPrice> GetAvgDirectorPrice()
{
  var query = from m in _session.Query<Movie>()
              group m by m.Director
              into g
              select new NameAndPrice(
                g.Key,
                g.Average(i => i.UnitPrice));
  return query.ToList();
}

static void RunQueries(ISession session)
{
  var queries = new Queries(session);

  Show("Movies directed by Spielberg:",
    queries.GetMoviesDirectedBy(
    "Steven Spielberg"));


  Show("Movies with Morgan Freeman:",
    queries.GetMoviesWith(
    "Morgan Freeman"));

  Show("This book:",
    queries.GetBookByISBN(
    "978-1-849513-04-3"));

  Show("Cheap products:",
    queries.GetProductByPrice(0M, 15M));

  Show("Movie Price List:",
    queries.GetMoviePriceList());

  Show("Average Movie Price:",
    queries.GetAverageMoviePrice());

  Show("Average Price by Director:",
    queries.GetAvgDirectorPrice());
}