private List<Song> GetArtistSongCollection(IEnumerable<Album> albumCollection) { var albumSongRepository = new SqlAlbumSongRepository(ConnectionString); var songRepository = new SqlSongRepository(ConnectionString); var songCollection = new List<Song>(); foreach (var albumSongs in albumCollection.Select(album => albumSongRepository.GetAlbumSongsByAlbumId(album.AlbumId))) { songCollection.AddRange( albumSongs.Select(albumSong => songRepository.SongTable.FirstOrDefault(x => x.SongId == albumSong.SongId)) .ToList()); } return songCollection; }