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140 lines
6.1 KiB
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140 lines
6.1 KiB
HTML
<p>表：<code>students</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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| student_id | int |
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| student_name | varchar |
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| major | varchar |
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+--------------+---------+
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student_id 是这张表的唯一主键。
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每一行包含有关学生及其学术专业的信息。
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</pre>
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<p>表：<code>study_sessions</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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| session_id | int |
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| student_id | int |
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| subject | varchar |
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| session_date | date |
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| hours_studied | decimal |
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+---------------+---------+
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session_id 是这张表的唯一主键。
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每一行代表一个学生针对特定学科的学习时段。
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</pre>
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<p>编写一个解决方案来找出遵循 <strong>螺旋学习模式</strong> 的学生——即那些持续学习多个学科并按循环周期进行学习的学生。</p>
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<ul>
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<li>螺旋学习模式意味着学生以重复的顺序学习至少 <code>3</code> 个 <strong>不同的学科</strong>。</li>
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<li>模式必须重复 <strong>至少</strong><strong> </strong><code>2</code><strong> 个完整周期</strong>（最少 <code>6</code> 次学习记录）。</li>
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<li>两次学习记录必须是间隔不超过 <code>2</code> 天的 <strong>连续日期</strong>。</li>
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<li>计算 <strong>循环长度</strong>（模式中不同的学科数量）。</li>
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<li>计算模式中所有学习记录的 <strong>总学习时长</strong>。</li>
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<li>仅包含循环长度 <strong>至少为 </strong><strong> </strong><code>3</code><strong> 门学科</strong> 的学生。</li>
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</ul>
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<p>返回结果表按循环长度 <strong>降序</strong> 排序，然后按总学习时间 <strong>降序</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>students 表：</p>
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<pre class="example-io">
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+------------+--------------+------------------+
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| student_id | student_name | major |
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+------------+--------------+------------------+
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| 1 | Alice Chen | Computer Science |
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| 2 | Bob Johnson | Mathematics |
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| 3 | Carol Davis | Physics |
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| 4 | David Wilson | Chemistry |
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| 5 | Emma Brown | Biology |
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+------------+--------------+------------------+
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</pre>
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<p>study_sessions 表：</p>
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<pre class="example-io">
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+------------+------------+------------+--------------+---------------+
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| session_id | student_id | subject | session_date | hours_studied |
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+------------+------------+------------+--------------+---------------+
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| 1 | 1 | Math | 2023-10-01 | 2.5 |
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| 2 | 1 | Physics | 2023-10-02 | 3.0 |
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| 3 | 1 | Chemistry | 2023-10-03 | 2.0 |
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| 4 | 1 | Math | 2023-10-04 | 2.5 |
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| 5 | 1 | Physics | 2023-10-05 | 3.0 |
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| 6 | 1 | Chemistry | 2023-10-06 | 2.0 |
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| 7 | 2 | Algebra | 2023-10-01 | 4.0 |
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| 8 | 2 | Calculus | 2023-10-02 | 3.5 |
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| 9 | 2 | Statistics | 2023-10-03 | 2.5 |
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| 10 | 2 | Geometry | 2023-10-04 | 3.0 |
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| 11 | 2 | Algebra | 2023-10-05 | 4.0 |
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| 12 | 2 | Calculus | 2023-10-06 | 3.5 |
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| 13 | 2 | Statistics | 2023-10-07 | 2.5 |
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| 14 | 2 | Geometry | 2023-10-08 | 3.0 |
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| 15 | 3 | Biology | 2023-10-01 | 2.0 |
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| 16 | 3 | Chemistry | 2023-10-02 | 2.5 |
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| 17 | 3 | Biology | 2023-10-03 | 2.0 |
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| 18 | 3 | Chemistry | 2023-10-04 | 2.5 |
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| 19 | 4 | Organic | 2023-10-01 | 3.0 |
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| 20 | 4 | Physical | 2023-10-05 | 2.5 |
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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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| student_id | student_name | major | cycle_length | total_study_hours |
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+------------+--------------+------------------+--------------+-------------------+
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| 2 | Bob Johnson | Mathematics | 4 | 26.0 |
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| 1 | Alice Chen | Computer Science | 3 | 15.0 |
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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>Alice Chen (student_id = 1):</strong>
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<ul>
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<li>学习序列：Math → Physics → Chemistry → Math → Physics → Chemistry</li>
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<li>模式：3 门学科（Math，Physics，Chemistry）重复 2 个完整周期</li>
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<li>连续日期：十月 1-6，没有超过 2 天的间隔</li>
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<li>循环长度：3 门学科</li>
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<li>总时间：2.5 + 3.0 + 2.0 + 2.5 + 3.0 + 2.0 = 15.0 小时</li>
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</ul>
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</li>
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<li><strong>Bob Johnson (student_id = 2):</strong>
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<ul>
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<li>学习序列：Algebra → Calculus → Statistics → Geometry → Algebra → Calculus → Statistics → Geometry</li>
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<li>模式：4 门学科（Algebra，Calculus，Statistics，Geometry）重复 2 个完整周期</li>
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<li>连续日期：十月 1-8，没有超过 2 天的间隔</li>
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<li>循环长度：4 门学科</li>
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<li>总时间：4.0 + 3.5 + 2.5 + 3.0 + 4.0 + 3.5 + 2.5 + 3.0 = 26.0 小时</li>
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</ul>
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</li>
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<li><strong>未包含学生：</strong>
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<ul>
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<li>Carol Davis (student_id = 3)：仅 2 门学科（生物，化学）- 未满足至少 3 门学科的要求</li>
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<li>David Wilson (student_id = 4)：仅 2 次学习课程，间隔 4 天 - 不符合连续日期要求</li>
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<li>Emma Brown (student_id = 5)：没有记录学习课程</li>
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</ul>
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</li>
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</ul>
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<p>结果表以 cycle_length 降序排序，然后以 total_study_hours 降序排序。</p>
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</div>
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