LeetCode MySQL-1084. Sales Analysis III

    AllenLi
    LeetCode MySQL

    Write an SQL query that reports the products that were only sold in the first quarter of 2019. That is, between 2019-01-01 and 2019-03-31 inclusive.
    Return the result table in any order.

    寫一個 SQL Query來報告"只有"在 2019-01-01 ~ 2019-03-31 之間販售的產品。
可任意排序結果。

    Table: Product

    +--------------+---------+
| Column Name  | Type    |
+--------------+---------+
| product_id   | int     |
| product_name | varchar |
| unit_price   | int     |
+--------------+---------+
product_id is the primary key of this table.
Each row of this table indicates the name and the price of each product.

    Table: Sales

    +-------------+---------+
| Column Name | Type    |
+-------------+---------+
| seller_id   | int     |
| product_id  | int     |
| buyer_id    | int     |
| sale_date   | date    |
| quantity    | int     |
| price       | int     |
+-------------+---------+
This table has no primary key, it can have repeated rows.
product_id is a foreign key to the Product table.
Each row of this table contains some information about one sale.

    Example 1:

    Input: 
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  |
+-----------+------------+----------+------------+----------+-------+
Output: 
+-------------+--------------+
| product_id  | product_name |
+-------------+--------------+
| 1           | S8           |
+-------------+--------------+
Explanation: 
The product with id 1 was only sold in the spring of 2019.
The product with id 2 was sold in the spring of 2019 but was also sold after the spring of 2019.
The product with id 3 was sold after spring 2019.
We return only product 1 as it is the product that was only sold in the spring of 2019.

    Solution:
    1. 選擇標題 p.product_id, p.product_name。
    2. 來自 Product 的 table。
    3. 加入 Sales 的 table。
    4. 將 p.product_id 與 s.product_id 做連結。
    5. 以 p.product_id 為群組。
    6. 且最大日期小於’2019-03-31’，同時最小日期大於’2019-01-01’。

    Code.1:

    SELECT p.product_id, p.product_name
	FROM Product AS p
    LEFT JOIN Sales AS s
		ON p.product_id = s.product_id
    GROUP BY p.product_id
    HAVING MAX(s.sale_date) <= '2019-03-31' AND MIN(s.sale_date) >= '2019-01-01';

    newSaleAnalysis

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