銷售表 Sales:
+-------------+-------+
| Column Name | Type |
+-------------+-------+
| sale_id | int |
| product_id | int |
| year | int |
| quantity | int |
| price | int |
+-------------+-------+
(sale_id, year) 是銷售表 Sales 的主鍵.
product_id 是產(chǎn)品表 Product 的外鍵.
注意: price 表示每單位價(jià)格
產(chǎn)品表 Product:
+--------------+---------+
| Column Name | Type |
+--------------+---------+
| product_id | int |
| product_name | varchar |
+--------------+---------+
product_id 是表的主鍵.
寫一條SQL 查詢語句獲取產(chǎn)品表 Product 中所有的 產(chǎn)品名稱 product name 以及 該產(chǎn)品在 Sales 表中相對應(yīng)的 上市年份 year 和 價(jià)格 price五芝。
示例:
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 |
+------------+--------------+
Result 表:
+--------------+-------+-------+
| product_name | year | price |
+--------------+-------+-------+
| Nokia | 2008 | 5000 |
| Nokia | 2009 | 5000 |
| Apple | 2011 | 9000 |
+--------------+-------+-------+
解答
用兩表連接即可
select S.product_name, P.year, P.product_id
from Sales as S
join Product as P
on S.product_id = P.product_id