1 题目描述
销售表 Sales:
+-------------+-------+
| Column Name | Type |
+-------------+-------+
| sale_id | int |
| product_id | int |
| year | int |
| quantity | int |
| price | int |
+-------------+-------+
(sale_id, year) 是销售表 Sales 的主键 (具有唯一值的列的组合)
product_id 是关联到产品表 Product 的外键 (reference 列)
该表的每一行显示 product_id 在某一年的销售情况
注意: price 表示每单位价格
产品表 Product:
+--------------+---------+
| Column Name | Type |
+--------------+---------+
| product_id | int |
| product_name | varchar |
+--------------+---------+
product_id 是表的主键 (具有唯一值的列)
该表的每一行表示每种产品的产品名称
编写解决方案, 以获取 Sales 表中所有 sale_id 对应的 product_name 以及该产品的所有 year 和 price
返回结果表 无顺序要求
2 测试用例
输入:
Sales 表:
+---------+------------+------+----------+-------+
| sale_id | product_id | year | quantity | price |
+---------+------------+------+----------+-------+
| 1 | 100 | 2008 | 10 | 5000 |
| 2 | 100 | 2009 | 12 | 5000 |
| 7 | 200 | 2011 | 15 | 9000 |
+---------+------------+------+----------+-------+
Product 表:
+------------+--------------+
| product_id | product_name |
+------------+--------------+
| 100 | Nokia |
| 200 | Apple |
| 300 | Samsung |
+------------+--------------+
输出:
+--------------+-------+-------+
| product_name | year | price |
+--------------+-------+-------+
| Nokia | 2008 | 5000 |
| Nokia | 2009 | 5000 |
| Apple | 2011 | 9000 |
+--------------+-------+-------+
3 解题思路
- 使用外连接, 将
Sales和Product关联起来
select p.product_name, s.year, s.price
from Sales as s
inner join Product as p on s.product_id = p.product_id;
查询结果
+------------+----+-----+
|product_name|year|price|
+------------+----+-----+
|Nokia |2009|5000 |
|Nokia |2008|5000 |
|Apple |2011|9000 |
+------------+----+-----+
