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			51 lines
		
	
	
		
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			51 lines
		
	
	
		
			1.8 KiB
		
	
	
	
		
			HTML
		
	
	
	
	
	
<p>表 <code>Activities</code>:</p>
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<pre>
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+-------------+---------+
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| 列名         | 类型    |
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+-------------+---------+
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| sell_date   | date    |
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| product     | varchar |
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+-------------+---------+
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此表没有主键,它可能包含重复项。
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此表的每一行都包含产品名称和在市场上销售的日期。
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</pre>
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<p> </p>
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<p>编写一个 SQL 查询来查找每个日期、销售的不同产品的数量及其名称。<br />
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每个日期的销售产品名称应按词典序排列。<br />
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返回按 <code>sell_date</code> 排序的结果表。<br />
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查询结果格式如下例所示。</p>
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<p> </p>
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<p><strong>示例 1:</strong></p>
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<pre>
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<code><strong>输入:</strong>
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Activities</code> 表:
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+------------+-------------+
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| sell_date  | product     |
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+------------+-------------+
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| 2020-05-30 | Headphone   |
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| 2020-06-01 | Pencil      |
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| 2020-06-02 | Mask        |
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| 2020-05-30 | Basketball  |
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| 2020-06-01 | Bible       |
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| 2020-06-02 | Mask        |
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| 2020-05-30 | T-Shirt     |
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+------------+-------------+
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<strong>输出:</strong>
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+------------+----------+------------------------------+
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| sell_date  | num_sold | products                     |
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+------------+----------+------------------------------+
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| 2020-05-30 | 3        | Basketball,Headphone,T-shirt |
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| 2020-06-01 | 2        | Bible,Pencil                 |
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| 2020-06-02 | 1        | Mask                         |
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+------------+----------+------------------------------+
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<strong>解释:</strong>
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对于2020-05-30,出售的物品是 (Headphone, Basketball, T-shirt),按词典序排列,并用逗号 ',' 分隔。
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对于2020-06-01,出售的物品是 (Pencil, Bible),按词典序排列,并用逗号分隔。
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对于2020-06-02,出售的物品是 (Mask),只需返回该物品名。</pre>
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