1. 题目

Table: Product

+--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| product_id   | int     |
| product_name | varchar |
| unit_price   | int     |
+--------------+---------+
product_id 是这个表的主键

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，报告2019年春季才售出的产品。
即仅在2019-01-01至2019-03-31（含）之间出售的商品。

查询结果格式如下所示：

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         | 2          | 3        | 2019-06-02 | 1        | 800   |
| 3         | 3          | 4        | 2019-05-13 | 2        | 2800  |
+-----------+------------+----------+------------+----------+-------+Result table:
+-------------+--------------+
| product_id  | product_name |
+-------------+--------------+
| 1           | S8           |
+-------------+--------------+
id为1的产品仅在2019年春季销售，其他两个产品在之后销售。

来源：力扣（LeetCode） 链接：https://leetcode-cn.com/problems/sales-analysis-iii
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

2. 解题

# Write your MySQL query statement below
select p.product_id, p.product_name
from Product p, Sales s
where p.product_id = s.product_id
group by s.product_id
having(sum(sale_date between '2019-01-01' and '2019.03-31') = count(*))

or

having sum(s.sale_date > '2019-03-31')=0 and sum(s.sale_date < '2019-01-01') = 0

having min(s.sale_date)>='2019-01-01' and max(s.sale_date) <= '2019-03-31'

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