这是我的table的描述

describe book;
+----------------+-------------+------+-----+---------+-------+
| Field          | Type        | Null | Key | Default | Extra |
+----------------+-------------+------+-----+---------+-------+
| isbn           | varchar(20) | NO   | PRI | NULL    |       |
| title          | varchar(30) | YES  |     | NULL    |       |
| date_published | date        | YES  |     | NULL    |       |
| publisher_id   | int(11)     | YES  |     | NULL    |       |
+----------------+-------------+------+-----+---------+-------+

describe author;
+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| author_id  | int(11)     | NO   | PRI | NULL    |       |
| first_name | varchar(20) | YES  |     | NULL    |       |
| last_name  | varchar(20) | YES  |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+

describe stored_on;
+--------------+-------------+------+-----+---------+-------+
| Field        | Type        | Null | Key | Default | Extra |
+--------------+-------------+------+-----+---------+-------+
| isbn         | varchar(20) | YES  |     | NULL    |       |
| total_copies | int(11)     | YES  |     | NULL    |       |
| shelf_number | int(11)     | YES  |     | NULL    |       |
| library      | varchar(20) | YES  | MUL | NULL    |       |
+--------------+-------------+------+-----+---------+-------+

describe written_by;
+-----------+-------------+------+-----+---------+-------+
| Field     | Type        | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| isbn      | varchar(20) | YES  | MUL | NULL    |       |
| author_id | int(11)     | YES  | MUL | NULL    |       |
+-----------+-------------+------+-----+---------+-------+

我试着显示书名，写那本书的作者名单，书架号，总份数，以及这本书所在的图书馆。

SELECT 
    b.title, 
    GROUP_CONCAT(CONCAT_WS(' ',a.first_name, a.last_name )) AS authors,
    so.shelf_number,
    so.total_copies,
    so.library
FROM 
    stored_on so 
LEFT OUTER JOIN book b ON so.isbn = b.isbn
LEFT OUTER JOIN written_by wb ON wb.isbn = so.isbn
LEFT OUTER JOIN author a ON wb.author_id = a.author_id
GROUP BY (b.title);

我不知道如何将我的数据分组到最后，这样会给我重复的标题/isbn。
示例：一个图书馆有一本书，而另一个图书馆有同一本书，我想打印出每本书的数据。它们都列在我的存储表上，我可以打印出所有的条目时，我不使用 GROUP_CONCAT ，但我在 authors 现场。
我好像搞不懂这个。