LINQ - 查询对象集合

internal class Book
	    {
            public Book(string title, int authorId, int year)
            {
                Title = title;
                AuthorId = authorId;
                PublishYear = year;
            }
            
            public string Title { get; set; }
            public int AuthorId { get; set; }
            public int PublishYear { get; set; }

            public override string ToString()
            {
                return string.Format("{0} - {1}", Title, PublishYear);
            }
	    }

        internal class Author
        {
            public Author(int id, string firstName, string lastName)
            {
                Id = id;
                FirstName = firstName;
                LastName = lastName;
            }
    
            public int Id { get; set; }
            public string FirstName { get; set; }
            public string LastName { get; set; }
    
            public void Foo()
            {
                List<Book> books = new List<Book>
                                   {
                                       new Book("Le Rhin", 1, 1842),
                                       new Book("Les Burgraves", 1, 1843),
                                       new Book("Napolé§|on le Petit", 1, 1852),
                                       new Book("Les Châtiments", 1, 1853),
                                       new Book("Les Contemplations", 1, 1856),
                                       new Book("Les Misé§|rables", 1, 1862)
                                   };

                List<Author> authors = new List<Author> {new Author(1, "Victor", "Hugo")};
            }
        }

var allBooks = from book in books select book;
foreach (Book book in allBooks)
{
    Console.WriteLine(book.ToString());
}

var ordered = from book in books
              orderby book.Title descending
              select book;

var ordered = from book in books 
              orderby book.PublishYear, book.Title descending
              select book;

var before1850 = from book in books 
                 where book.PublishYear < 1850
                 select book;

var dateRange = from book in books 
                where book.PublishYear >= 1850 
                    && book.PublishYear <= 1855
                select book;

var justTitlesAfter1850 = from book in books
                          where book.PublishYear > 1850
                          select book.Title;

var withAuthors = from book in books
                  join author in authors on book.AuthorId equals author.Id
                  select
                      new
                      {
                          Book = book.Title,
                          Author = string.Format("{0} {1}", author.FirstName, author.LastName)
                      };

Console.WriteLine("Join with authors:");
foreach (var bookAndAuthor in withAuthors)
{
    Console.WriteLine("{0}, {1}", bookAndAuthor.Book, bookAndAuthor.Author);
}