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***规则： --- 不要使用任何类型的连接，也不要使用相关子查询。--- 不要使用逗号连接。--- 如果您使用加入，您将不会获得该任务的积分。From 子句将仅引用一个表。--- 不要使用变量。

***这是我的问题：显示某人订购的任何书籍的书籍 ID 和标题，并且该书籍既是 SQL 书籍又是数据库书籍。使用 Topic_id 过滤 DB 和 SQL。按 book_id 排序。

***我的回答：

 select book_id, title
  From a_bkinfo.books
  Where book_id IN
    (Select book_id
     From a_bkinfo.book_topics
     Where topic_id = 'DB')
 And book_id in
    (Select book_id
     From a_bkinfo.book_topics
     Where topic_id = 'SQL')
     order by book_id;

我在这个问题上收到了-2。我的老师回复：-2 *没有检查这本书是否已被订购。

***以下是相关表格。* 表格：

 ---- create order_details ------
 create  table   a_bkorders.order_details (
 order_id          integer          not null 
, order_line        integer          not null 
, book_id           integer          not null 
, quantity          integer          not null 
, order_price       numeric(6,2)     not null   
, constraint bk_orderline_pk         primary key (order_id, order_line)
, constraint bk_orderline_order_fk   foreign key (order_id) 
             references a_bkorders.order_headers(order_id) on delete cascade
, constraint bk_orderline_book_fk    foreign key (book_id )  
           references a_bkinfo.books(book_id)
, constraint bk_quantity_ck          check (quantity > 0) 
, constraint bk_ordprice_ck          check (order_price >= 0)

)引擎= INNODB；

---- create book_topics ----
 create  table a_bkinfo.book_topics (
 book_id           integer          not null
, topic_id          varchar(5)       not null  
, constraint bk_book_topics_pk        primary key (book_id, topic_id)
, constraint bk_books_topics_fk      foreign key(topic_id) 
           references a_bkinfo.topics(topic_id)
, constraint bk_books_id_fk          foreign key(book_id) 
           references a_bkinfo.books(book_id)

)引擎= INNODB；

------ create books ------
create table a_bkinfo.books (
book_id           integer          not null
, title             varchar(75)      not null 
, publ_id           integer          null
, year_publd        integer          not null
, isbn              varchar(17)      null
, page_count        integer          null  
, list_price        numeric(6,2)     null  
, constraint bk_books_pk             primary key (book_id)
, constraint bk_books_publ_fk        foreign key(publ_id) 
           references a_bkinfo.publishers  (publ_id)
, constraint book_id_range           check (book_id > 1000)
, constraint bk_page_count_ck        check (page_count >= 0)
, constraint bk_price_ck             check (list_price >= 0)             
, constraint bk_books_year_ck        check (year_publd >= 1850)
)engine = INNODB;
4

1 回答 1

1 
and book_id in 
    ( select d.book_id 
        from a_bkorders.order_details d
       where d.quantity > 0 
    )

显示销量最多的书籍的ID和书名；包括关系。对于此查询，使用已售总数量。在确定一本书的销量时

没有任何 JOIN 操作或相关子查询，这将返回指定的结果集：

SELECT b.book_id
     , b.title
  FROM a_bkinfo.books b
 WHERE b.book_id IN
       ( 
         SELECT d.book_id
           FROM a_bkorders.order_details d
          GROUP BY d.book_id
         HAVING SUM(d.quantity) =
                (
                  SELECT MAX(t.tot_quantity)
                    FROM (  
                           SELECT s.book_id
                                , SUM(s.quantity) AS tot_quantity
                             FROM a_bkorders.order_details s
                            GROUP BY s.book_id
                         ) t
                )
       )

注意MySQL 不强制执行 CHECK 约束。

于 2013-11-03T03:35:23.183 回答