表:library_books
+------------------+---------+ | Column Name | Type | +------------------+---------+ | book_id | int | | title | varchar | | author | varchar | | genre | varchar | | publication_year | int | | total_copies | int | +------------------+---------+ book_id 是这张表的唯一主键。 每一行包含图书馆中一本书的信息,包括图书馆拥有的副本总数。
表:borrowing_records
+---------------+---------+ | Column Name | Type | +---------------+---------+ | record_id | int | | book_id | int | | borrower_name | varchar | | borrow_date | date | | return_date | date | +---------------+---------+ record_id 是这张表的唯一主键。 每一行代表一笔借阅交易并且如果这本书目前被借出并且还没有被归还,return_date 为 NULL。
编写一个解决方案以找到 所有 当前被借出(未归还) 且图书馆中 无可用副本 的书籍。
return_date
为 NULL,那么这本书被认为 当前是借出的。返回结果表按当前借阅者数量 降序 排列,然后按书名 升序 排列。
结果格式如下所示。
示例:
输入:
library_books 表:
+---------+------------------------+------------------+----------+------------------+--------------+ | book_id | title | author | genre | publication_year | total_copies | +---------+------------------------+------------------+----------+------------------+--------------+ | 1 | The Great Gatsby | F. Scott | Fiction | 1925 | 3 | | 2 | To Kill a Mockingbird | Harper Lee | Fiction | 1960 | 3 | | 3 | 1984 | George Orwell | Dystopian| 1949 | 1 | | 4 | Pride and Prejudice | Jane Austen | Romance | 1813 | 2 | | 5 | The Catcher in the Rye | J.D. Salinger | Fiction | 1951 | 1 | | 6 | Brave New World | Aldous Huxley | Dystopian| 1932 | 4 | +---------+------------------------+------------------+----------+------------------+--------------+
borrowing_records 表:
+-----------+---------+---------------+-------------+-------------+ | record_id | book_id | borrower_name | borrow_date | return_date | +-----------+---------+---------------+-------------+-------------+ | 1 | 1 | Alice Smith | 2024-01-15 | NULL | | 2 | 1 | Bob Johnson | 2024-01-20 | NULL | | 3 | 2 | Carol White | 2024-01-10 | 2024-01-25 | | 4 | 3 | David Brown | 2024-02-01 | NULL | | 5 | 4 | Emma Wilson | 2024-01-05 | NULL | | 6 | 5 | Frank Davis | 2024-01-18 | 2024-02-10 | | 7 | 1 | Grace Miller | 2024-02-05 | NULL | | 8 | 6 | Henry Taylor | 2024-01-12 | NULL | | 9 | 2 | Ivan Clark | 2024-02-12 | NULL | | 10 | 2 | Jane Adams | 2024-02-15 | NULL | +-----------+---------+---------------+-------------+-------------+
输出:
+---------+------------------+---------------+-----------+------------------+-------------------+ | book_id | title | author | genre | publication_year | current_borrowers | +---------+------------------+---------------+-----------+------------------+-------------------+ | 1 | The Great Gatsby | F. Scott | Fiction | 1925 | 3 | | 3 | 1984 | George Orwell | Dystopian | 1949 | 1 | +---------+------------------+---------------+-----------+------------------+-------------------+
解释:
输出表以 current_borrowers 降序排序,然后以 book_title 升序排序。