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题目介绍: 销售分析 II sales-analysis-ii
难度简单13
SQL架构
Table:
Product
+--------------+---------+
| Column Name | Type |
+--------------+---------+
| product_id | int |
| product_name | varchar |
| unit_price | int |
+--------------+---------+
product_id 是这张表的主键
Table:
Sales
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| seller_id | int |
| product_id | int |
| buyer_id | int |
| sale_date | date |
| quantity | int |
| price | int |
+------ ------+---------+
这个表没有主键,它可以有重复的行.
product_id 是 Product 表的外键.
编写一个 SQL 查询,查询购买了 S8 手机却没有购买 iPhone 的买家。注意这里 S8 和 iPhone 是 Product 表中的产品。
查询结果格式如下图表示:
``` Product table: +------------+--------------+------------+ | product_id | product_name | unit_price | +------------+--------------+------------+ | 1 | S8 | 1000 | | 2 | G4 | 800 | | 3 | iPhone | 1400 | +------------+--------------+------------+
Sales table: +-----------+------------+----------+------------+----------+-------+ | seller_id | product_id | buyer_id | sale_date | quantity | price | +-----------+------------+----------+------------+----------+-------+ | 1 | 1 | 1 | 2019-01-21 | 2 | 2000 | | 1 | 2 | 2 | 2019-02-17 | 1 | 800 | | 2 | 1 | 3 | 2019-06-02 | 1 | 800 | | 3 | 3 | 3 | 2019-05-13 | 2 | 2800 | +-----------+------------+----------+------------+----------+-------+
Result table: +-------------+ | buyer_id | +-------------+ | 1 | +-------------+ id 为 1 的买家购买了一部 S8,但是却没有购买 iPhone,而 id 为 3 的买家却同时购买了这 2 部手机。 ```
sql
select t.buyer_id from(
select s.buyer_id, p.product_name
from sales s
inner join
product p
on s.product_id=p.product_id and (p.product_name='S8' or p.product_name='iPhone')
group by s.buyer_id
having count(distinct p.product_name) = 1
) t
where t.product_name='S8'
效率低
sql
select s.buyer_id
from sales as s left join product as p
on s.product_id=p.product_id
group by buyer_id
having sum(p.product_name='S8')>0 and sum(p.product_name='iPhone')=0