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148 lines
5.3 KiB
HTML
148 lines
5.3 KiB
HTML
<p>表：<code>ProductPurchases</code></p>
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<pre>
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+-------------+------+
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| Column Name | Type |
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+-------------+------+
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| user_id | int |
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| product_id | int |
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| quantity | int |
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+-------------+------+
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(user_id, product_id) 是这张表的唯一主键。
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每一行代表用户以特定数量购买的一种产品。
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</pre>
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<p>表：<code>ProductInfo</code></p>
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<pre>
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+-------------+---------+
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| Column Name | Type |
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+-------------+---------+
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| product_id | int |
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| category | varchar |
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| price | decimal |
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+-------------+---------+
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product_id 是这张表的唯一主键。
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每一行表示一件商品的类别和价格。
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</pre>
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<p>亚马逊想要了解不同产品类别的购物模式。编写一个解决方案：</p>
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<ol>
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<li>查找所有 <strong>类别对</strong>（其中 <code>category1</code> < <code>category2</code>）</li>
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<li>对于 <strong>每个类别对</strong>，确定 <strong>同时</strong> 购买了两类别产品的 <strong>不同用户</strong> 数量</li>
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</ol>
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<p>如果至少有 <code>3</code> 个不同的客户购买了两个类别的产品，则类别对被视为 <strong>可报告的</strong>。</p>
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<p>返回可报告类别对的结果表以<em> </em><strong>customer_count</strong><em> </em><strong>降序</strong><em> </em>排序，并且为了防止排序持平，以<em> </em><strong>category1 </strong>字典序<strong> 升序</strong> 排序，然后以 <strong>category2 升序</strong> 排序。</p>
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<p>结果格式如下所示。</p>
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<p> </p>
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<p><strong class="example">示例：</strong></p>
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<div class="example-block">
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<p><strong>输入：</strong></p>
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<p>ProductPurchases 表：</p>
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<pre class="example-io">
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+---------+------------+----------+
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| user_id | product_id | quantity |
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+---------+------------+----------+
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| 1 | 101 | 2 |
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| 1 | 102 | 1 |
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| 1 | 201 | 3 |
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| 1 | 301 | 1 |
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| 2 | 101 | 1 |
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| 2 | 102 | 2 |
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| 2 | 103 | 1 |
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| 2 | 201 | 5 |
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| 3 | 101 | 2 |
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| 3 | 103 | 1 |
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| 3 | 301 | 4 |
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| 3 | 401 | 2 |
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| 4 | 101 | 1 |
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| 4 | 201 | 3 |
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| 4 | 301 | 1 |
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| 4 | 401 | 2 |
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| 5 | 102 | 2 |
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| 5 | 103 | 1 |
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| 5 | 201 | 2 |
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| 5 | 202 | 3 |
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+---------+------------+----------+
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</pre>
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<p>ProductInfo 表：</p>
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<pre class="example-io">
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+------------+-------------+-------+
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| product_id | category | price |
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+------------+-------------+-------+
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| 101 | Electronics | 100 |
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| 102 | Books | 20 |
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| 103 | Books | 35 |
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| 201 | Clothing | 45 |
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| 202 | Clothing | 60 |
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| 301 | Sports | 75 |
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| 401 | Kitchen | 50 |
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+------------+-------------+-------+
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</pre>
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<p><strong>输出：</strong></p>
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<pre class="example-io">
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+-------------+-------------+----------------+
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| category1 | category2 | customer_count |
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+-------------+-------------+----------------+
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| Books | Clothing | 3 |
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| Books | Electronics | 3 |
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| Clothing | Electronics | 3 |
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| Electronics | Sports | 3 |
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+-------------+-------------+----------------+
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</pre>
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<p><strong>解释：</strong></p>
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<ul>
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<li><strong>Books-Clothing</strong>:
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<ul>
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<li>用户 1 购买来自 Books (102) 和 Clothing (201) 的商品</li>
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<li>用户 2 购买来自 Books (102, 103) 和 Clothing (201) 的商品</li>
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<li>用户 5 购买来自 Books (102, 103) 和 Clothing (201, 202) 的商品</li>
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<li>共计：3 个用户购买同一类别的商品</li>
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</ul>
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</li>
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<li><strong>Books-Electronics</strong>:
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<ul>
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<li>用户 1 购买来自 Books (102) 和 Electronics (101) 的商品</li>
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<li>用户 2 购买来自 Books (102, 103) 和 Electronics (101) 的商品</li>
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<li>用户 3 购买来自 Books (103) 和 Electronics (101) 的商品</li>
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<li>共计：3 个消费者购买同一类别的商品</li>
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</ul>
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</li>
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<li><strong>Clothing-Electronics</strong>:
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<ul>
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<li>用户 1 购买来自 Clothing (201) 和 Electronics (101) 的商品</li>
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<li>用户 2 购买来自 Clothing (201) 和 Electronics (101) 的商品</li>
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<li>用户 4 购买来自 Clothing (201) 和 Electronics (101) 的商品</li>
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<li>共计：3 个消费者购买同一类别的商品</li>
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</ul>
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</li>
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<li><strong>Electronics-Sports</strong>:
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<ul>
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<li>用户 1 购买来自 Electronics (101) 和 Sports (301) 的商品</li>
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<li>用户 3 购买来自 Electronics (101) 和 Sports (301) 的商品</li>
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<li>用户 4 购买来自 Electronics (101) 和 Sports (301) 的商品</li>
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<li>共计：3 个消费者购买同一类别的商品</li>
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</ul>
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</li>
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<li>其它类别对比如 Clothing-Sports（只有 2 个消费者：用户 1 和 4）和 Books-Kitchen（只有 1 个消费者：用户 3）共同的消费者少于 3 个，因此不包含在结果内。</li>
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</ul>
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<p>结果按 customer_count 降序排列。由于所有对都有相同的客户数量 3，它们按 category1（然后是 category2）升序排列。</p>
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</div>
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