How to get average with orderBy Desc in Laravel 5

Question

I have 2 tables in my database.

books and ratings

in books id, name

in ratings

Answer 1

Via Collections*

    $books = Book::with('ratings')
        ->get()
        ->sortBy(function($bk, $key) {
            if($bk->rating) {
                return $bk->rating->rating;
            }
            return null;
        });

Via Joins

  $books = Book::join('rating', 'rating.book_id', '=', 'book.id')
                 ->orderBy('ratings.rating', 'desc')
                 ->select('books.*')
                 ->get();