GROUP BY-klausul med alias?

OPDATERET2

1. Det ser ud til, at du ikke behøver at inkludere TotalSales i GROUP BY. Når du ser på din forespørgsel, giver det bare ingen mening. Bare forkast det fra det indre udvalg.

2. For at inkludere bøger, der ikke er blevet solgt, skal du bruge en outer join

Når det er sagt, kan din forespørgsel se ud

SELECT COALESCE(author_id, 'All Authors') author_id
     , COALESCE(book_id, IF(author_id IS NULL, 'All Books', 'Subtotal')) book_id
     , COALESCE(total_quantity, 'No books') total_quantity
     , COALESCE(total_sales, 'No Sales') total_sales   
 FROM 
(    
 SELECT author_id 
      , b.book_id 
      , SUM(quantity) total_quantity  
      , SUM(quantity * order_price) total_sales   
   FROM book_authors b LEFT JOIN order_details d
     ON b.book_id = d.book_id
  WHERE author_sequence = 1           
  GROUP BY Author_id, Book_ID WITH ROLLUP  -- you don't need TotalSales here
) q;

Eksempeloutput:

+-------------+-----------+----------------+-------------+
| author_id   | book_id   | total_quantity | total_sales |
+-------------+-----------+----------------+-------------+
| 1           | 1         | 12             | 278.50      |
| 1           | 3         | No books       | No Sales    |
| 1           | Subtotal  | 12             | 278.50      |
| 3           | 2         | 5              | 75.75       |
| 3           | Subtotal  | 5              | 75.75       |
| All Authors | All Books | 17             | 354.25      |
+-------------+-----------+----------------+-------------+

Her er SQLFiddle demo