试图制作一张表格,其中单本书的成本高于所有书籍的平均成本
SELECT book_num, book_title, book_cost
FROM (SELECT book_num, book_title, book_cost, Avg(book_cost) AS AVGPRICE
FROM book
GROUP BY book_num, book_title, book_cost)
WHERE book_cost > AVGPRICE
ORDER BY book_title;