Question

我有三张桌子：

author (columns: aut_id, aut_name)
book (columns: book_id, book_title)
authorbook (linking table, columns: aut_id, book_id)

每位作者都可以与一本或多本书联系在一起每本书都可以与一位或多位作者联系我想根据名称和作者的确切数量来选择一本书。

表格结构：

author    
aut_id    |   aut_name
1             Aname
2             Bname
3             Cname

book    
book_id    |  book_title (the titles are identical on purpose) 
1             Atitle
2             Atitle
3             Atitle

authorbook
aut_id    |   book_id 
1             1
1             2
2             2
1             3
2             3
3             3

这是我的代码（我遗漏了作者表以便更好地澄清）：

SELECT authorbook.book_id 
FROM authorbook 
INNER JOIN book
ON authorbook.book_id = book.book_id
WHERE book_title='Atitle'
AND FIND_IN_SET (authorbook.aut_id,'1,2')
GROUP BY authorbook.book_id
HAVING (COUNT(authorbook.aut_id)=2)

问题：此代码不仅返回带有authorbook.book_id(2)的所需authorbook.aut_ids (1,2)，还返回带有authorbook.book_id(3)的{{1}}。

问题：我如何authorbook.aut_ids (1,2,3)一本书与SELECT条款中的作者完全相关（并且没有其他作者）？非常感谢你的帮助！

Answer 1

试试这个：

SELECT a.book_id
FROM authorbook a
INNER JOIN book b
ON a.book_id = b.book_id
WHERE b.book_title='Atitle'
  AND FIND_IN_SET (a.aut_id,'1,2')
GROUP BY a.book_id
HAVING COUNT(DISTINCT a.aut_id) = 2
   AND COUNT(DISTINCT a.aut_id) = (SELECT COUNT(DISTINCT a2.aut_id)
                                   FROM authorbook a2 
                                   WHERE a2.book_id = a.book_id);

SQL Fiddle Demo

Answer 2

这应该有效

SELECT COUNT(aut_id) AS authors, book_id FROM (SELECT authorbook.*
FROM authorbook 
INNER JOIN book
ON authorbook.book_id = book.book_id
WHERE book_title='Atitle') AS t1 GROUP BY book_id HAVING authors='2'

MySQL根据特定的字段值和行数选择多行

2 个答案:

SQL Fiddle Demo