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题目介绍: 小众书籍 unpopular-books
难度中等
SQL架构
书籍表
Books
:
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| book_id | int |
| name | varchar |
| available_from | date |
+----------------+---------+
book_id 是这个表的主键。
订单表
Orders
:
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| order_id | int |
| book_id | int |
| quantity | int |
| dispatch_date | date |
+----------------+---------+
order_id 是这个表的主键。
book_id 是 Books 表的外键。
你需要写一段 SQL 命令,筛选出过去一年中订单总量 少于10本 的 书籍 。
注意:不考虑 上架(available from)距今 不满一个月 的书籍。并且 假设今天是 2019-06-23 。
Write an SQL query that reports the books that have sold less than 10 copies in the last year, excluding books that have been available for less than 1 month from today. Assume today is 2019-06-23.
下面是样例输出结果:
``` Books 表: +---------+--------------------+----------------+ | book_id | name | available_from | +---------+--------------------+----------------+ | 1 | "Kalila And Demna" | 2010-01-01 | | 2 | "28 Letters" | 2012-05-12 | | 3 | "The Hobbit" | 2019-06-10 | | 4 | "13 Reasons Why" | 2019-06-01 | | 5 | "The Hunger Games" | 2008-09-21 | +---------+--------------------+----------------+
Orders 表: +----------+---------+----------+---------------+ | order_id | book_id | quantity | dispatch_date | +----------+---------+----------+---------------+ | 1 | 1 | 2 | 2018-07-26 | | 2 | 1 | 1 | 2018-11-05 | | 3 | 3 | 8 | 2019-06-11 | | 4 | 4 | 6 | 2019-06-05 | | 5 | 4 | 5 | 2019-06-20 | | 6 | 5 | 9 | 2009-02-02 | | 7 | 5 | 8 | 2010-04-13 | +----------+---------+----------+---------------+
Result 表: +-----------+--------------------+ | book_id | name | +-----------+--------------------+ | 1 | "Kalila And Demna" | | 2 | "28 Letters" | | 5 | "The Hunger Games" | +-----------+--------------------+ ```
这题中英文 都有歧义,看结果进行分析
sql
SELECT a.book_id, a.name
FROM books a LEFT JOIN orders b ON a.book_id=b.book_id
AND dispatch_date BETWEEN DATE_ADD('2019-06-23', INTERVAL -1 YEAR) AND '2019-06-23'
WHERE a.available_from <= DATE_ADD('2019-06-23',INTERVAL -1 MONTH)
GROUP BY a.book_id, a.name
HAVING SUM(IFNULL(b.quantity,0)) < 10
ORDER BY a.book_id;
此题有坑,首先订单近一年,再者quantity为null,还有近一月出版,sum不是订单是本数 还有就是date_add这个函数在hive里和mysql语法上有点小区别