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feat: add solutions to lc problem: No.3188 (#3124)
No.3188.Find Top Scoring Students II
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‎solution/3100-3199/3188.Find Top Scoring Students II/README.md

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---
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comments: true
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difficulty: 困难
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edit_url: https://github.com/doocs/leetcode/edit/main/solution/3100-3199/3188.Find%20Top%20Scoring%20Students%20II/README.md
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---
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<!-- problem:start -->
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# [3188. Find Top Scoring Students II 🔒](https://leetcode.cn/problems/find-top-scoring-students-ii)
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[English Version](/solution/3100-3199/3188.Find%20Top%20Scoring%20Students%20II/README_EN.md)
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## 题目描述
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<!-- description:start -->
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<p>Table: <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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| name | varchar |
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| major | varchar |
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+-------------+----------+
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student_id is the primary key for this table.
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Each row contains the student ID, student name, and their major.
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</pre>
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<p>Table: <code>courses</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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| course_id | int |
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| name | varchar |
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| credits | int |
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| major | varchar |
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| mandatory | enum |
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+-------------+-------------------+
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course_id is the primary key for this table.
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mandatory is an enum type of (&#39;Yes&#39;, &#39;No&#39;).
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Each row contains the course ID, course name, credits, major it belongs to, and whether the course is mandatory.
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</pre>
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<p>Table: <code>enrollments</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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| course_id | int |
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| semester | varchar |
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| grade | varchar |
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| GPA | decimal |
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+-------------+----------+
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(student_id, course_id, semester) is the primary key (combination of columns with unique values) for this table.
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Each row contains the student ID, course ID, semester, and grade received.
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</pre>
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<p>Write a solution to find the students who meet the following criteria:</p>
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<ul>
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<li>Have<strong> taken all mandatory courses</strong> and <strong>at least two</strong> elective courses offered in <strong>their major.</strong></li>
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<li>Achieved a grade of <strong>A</strong>&nbsp;in <strong>all mandatory courses</strong> and at least <strong>B</strong>&nbsp;in<strong> elective courses</strong>.</li>
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<li>Maintained an average <code>GPA</code> of at least&nbsp;<code>2.5</code> across all their courses (including those outside their major).</li>
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</ul>
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<p>Return <em>the result table ordered by</em> <code>student_id</code> <em>in <strong>ascending</strong> order</em>.</p>
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<p>&nbsp;</p>
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<p><strong class="example">Example:</strong></p>
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<div class="example-block">
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<p><strong>Input:</strong></p>
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<p>students table:</p>
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<pre class="example-io">
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+------------+------------------+------------------+
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| student_id | name | major |
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+------------+------------------+------------------+
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| 1 | Alice | Computer Science |
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| 2 | Bob | Computer Science |
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| 3 | Charlie | Mathematics |
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| 4 | David | Mathematics |
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+------------+------------------+------------------+
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</pre>
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<p>courses table:</p>
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<pre class="example-io">
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+-----------+-------------------+---------+------------------+----------+
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| course_id | name | credits | major | mandatory|
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+-----------+-------------------+---------+------------------+----------+
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| 101 | Algorithms | 3 | Computer Science | yes |
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| 102 | Data Structures | 3 | Computer Science | yes |
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| 103 | Calculus | 4 | Mathematics | yes |
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| 104 | Linear Algebra | 4 | Mathematics | yes |
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| 105 | Machine Learning | 3 | Computer Science | no |
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| 106 | Probability | 3 | Mathematics | no |
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| 107 | Operating Systems | 3 | Computer Science | no |
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| 108 | Statistics | 3 | Mathematics | no |
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+-----------+-------------------+---------+------------------+----------+
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</pre>
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<p>enrollments table:</p>
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<pre class="example-io">
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+------------+-----------+-------------+-------+-----+
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| student_id | course_id | semester | grade | GPA |
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+------------+-----------+-------------+-------+-----+
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| 1 | 101 | Fall 2023 | A | 4.0 |
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| 1 | 102 | Spring 2023 | A | 4.0 |
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| 1 | 105 | Spring 2023 | A | 4.0 |
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| 1 | 107 | Fall 2023 | B | 3.5 |
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| 2 | 101 | Fall 2023 | A | 4.0 |
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| 2 | 102 | Spring 2023 | B | 3.0 |
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| 3 | 103 | Fall 2023 | A | 4.0 |
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| 3 | 104 | Spring 2023 | A | 4.0 |
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| 3 | 106 | Spring 2023 | A | 4.0 |
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| 3 | 108 | Fall 2023 | B | 3.5 |
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| 4 | 103 | Fall 2023 | B | 3.0 |
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| 4 | 104 | Spring 2023 | B | 3.0 |
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+------------+-----------+-------------+-------+-----+
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</pre>
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<p><strong>Output:</strong></p>
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<pre class="example-io">
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+------------+
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| student_id |
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+------------+
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| 1 |
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| 3 |
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+------------+
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</pre>
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<p><strong>Explanation:</strong></p>
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<ul>
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<li>Alice (student_id 1) is a Computer Science major and has taken both Algorithms&nbsp;and Data Structures, receiving an A&nbsp;in both. She has also taken Machine Learning&nbsp;and Operating Systems&nbsp;as electives, receiving an A&nbsp;and B&nbsp;respectively.</li>
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<li>Bob (student_id 2) is a Computer Science major but did not receive an A&nbsp;in all required courses.</li>
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<li>Charlie (student_id 3) is a Mathematics major and has taken both Calculus&nbsp;and Linear Algebra, receiving an A&nbsp;in both. He has also taken Probability&nbsp;and Statistics&nbsp;as electives, receiving an A&nbsp;and B&nbsp;respectively.</li>
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<li>David (student_id 4) is a Mathematics major but did not receive an A&nbsp;in all required courses.</li>
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</ul>
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<p><strong>Note:</strong> Output table is ordered by student_id in ascending order.</p>
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</div>
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<!-- description:end -->
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## 解法
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<!-- solution:start -->
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### 方法一：连接 + 分组 + 条件过滤
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我们首先计算出每个学生的平均 GPA，记录在临时表 `T` 中。
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然后，我们将 `students` 表与 `courses` 表按照 `major` 进行连接，然后与 `T` 表按照 `student_id` 进行连接，再与 `enrollments` 表按照 `student_id` 和 `course_id` 进行左连接。
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接下来，我们筛选出平均 GPA 大于等于 2.5 的学生，并按照学生 ID 进行分组，然后使用 `HAVING` 子句过滤出符合条件的学生，最后按照学生 ID 进行排序。
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<!-- tabs:start -->
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#### MySQL
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```sql
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# Write your MySQL query statement below
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WITH
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T AS (
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SELECT student_id, AVG(GPA) AS avg_gpa
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FROM enrollments
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GROUP BY 1
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)
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SELECT student_id
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FROM
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students
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JOIN courses USING (major)
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JOIN T USING (student_id)
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LEFT JOIN enrollments USING (student_id, course_id)
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WHERE avg_gpa >= 2.5
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GROUP BY 1
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HAVING
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SUM(mandatory = 'yes' AND grade = 'A') = SUM(mandatory = 'yes')
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AND SUM(mandatory = 'no' AND grade IS NOT NULL) = SUM(mandatory = 'no' AND grade IN ('A', 'B'))
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AND SUM(mandatory = 'no' AND grade IS NOT NULL) >= 2
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ORDER BY 1;
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- problem:end -->

‎solution/3100-3199/3188.Find Top Scoring Students II/README_EN.md

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---
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comments: true
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difficulty: Hard
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edit_url: https://github.com/doocs/leetcode/edit/main/solution/3100-3199/3188.Find%20Top%20Scoring%20Students%20II/README_EN.md
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---
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<!-- problem:start -->
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# [3188. Find Top Scoring Students II 🔒](https://leetcode.com/problems/find-top-scoring-students-ii)
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[中文文档](/solution/3100-3199/3188.Find%20Top%20Scoring%20Students%20II/README.md)
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## Description
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<!-- description:start -->
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<p>Table: <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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| name | varchar |
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| major | varchar |
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+-------------+----------+
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student_id is the primary key for this table.
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Each row contains the student ID, student name, and their major.
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</pre>
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<p>Table: <code>courses</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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| course_id | int |
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| name | varchar |
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| credits | int |
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| major | varchar |
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| mandatory | enum |
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+-------------+-------------------+
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course_id is the primary key for this table.
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mandatory is an enum type of (&#39;Yes&#39;, &#39;No&#39;).
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Each row contains the course ID, course name, credits, major it belongs to, and whether the course is mandatory.
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</pre>
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<p>Table: <code>enrollments</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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| course_id | int |
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| semester | varchar |
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| grade | varchar |
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| GPA | decimal |
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+-------------+----------+
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(student_id, course_id, semester) is the primary key (combination of columns with unique values) for this table.
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Each row contains the student ID, course ID, semester, and grade received.
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</pre>
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<p>Write a solution to find the students who meet the following criteria:</p>
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<ul>
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<li>Have<strong> taken all mandatory courses</strong> and <strong>at least two</strong> elective courses offered in <strong>their major.</strong></li>
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<li>Achieved a grade of <strong>A</strong>&nbsp;in <strong>all mandatory courses</strong> and at least <strong>B</strong>&nbsp;in<strong> elective courses</strong>.</li>
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<li>Maintained an average <code>GPA</code> of at least&nbsp;<code>2.5</code> across all their courses (including those outside their major).</li>
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</ul>
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<p>Return <em>the result table ordered by</em> <code>student_id</code> <em>in <strong>ascending</strong> order</em>.</p>
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<p>&nbsp;</p>
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<p><strong class="example">Example:</strong></p>
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<div class="example-block">
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<p><strong>Input:</strong></p>
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<p>students table:</p>
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<pre class="example-io">
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+------------+------------------+------------------+
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| student_id | name | major |
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+------------+------------------+------------------+
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| 1 | Alice | Computer Science |
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| 2 | Bob | Computer Science |
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| 3 | Charlie | Mathematics |
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| 4 | David | Mathematics |
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+------------+------------------+------------------+
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</pre>
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<p>courses table:</p>
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<pre class="example-io">
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+-----------+-------------------+---------+------------------+----------+
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| course_id | name | credits | major | mandatory|
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+-----------+-------------------+---------+------------------+----------+
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| 101 | Algorithms | 3 | Computer Science | yes |
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| 102 | Data Structures | 3 | Computer Science | yes |
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| 103 | Calculus | 4 | Mathematics | yes |
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| 104 | Linear Algebra | 4 | Mathematics | yes |
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| 105 | Machine Learning | 3 | Computer Science | no |
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| 106 | Probability | 3 | Mathematics | no |
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| 107 | Operating Systems | 3 | Computer Science | no |
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| 108 | Statistics | 3 | Mathematics | no |
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+-----------+-------------------+---------+------------------+----------+
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</pre>
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<p>enrollments table:</p>
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<pre class="example-io">
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+------------+-----------+-------------+-------+-----+
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| student_id | course_id | semester | grade | GPA |
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+------------+-----------+-------------+-------+-----+
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| 1 | 101 | Fall 2023 | A | 4.0 |
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| 1 | 102 | Spring 2023 | A | 4.0 |
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| 1 | 105 | Spring 2023 | A | 4.0 |
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| 1 | 107 | Fall 2023 | B | 3.5 |
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| 2 | 101 | Fall 2023 | A | 4.0 |
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| 2 | 102 | Spring 2023 | B | 3.0 |
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| 3 | 103 | Fall 2023 | A | 4.0 |
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| 3 | 104 | Spring 2023 | A | 4.0 |
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| 3 | 106 | Spring 2023 | A | 4.0 |
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| 3 | 108 | Fall 2023 | B | 3.5 |
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| 4 | 103 | Fall 2023 | B | 3.0 |
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| 4 | 104 | Spring 2023 | B | 3.0 |
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+------------+-----------+-------------+-------+-----+
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</pre>
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<p><strong>Output:</strong></p>
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<pre class="example-io">
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+------------+
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| student_id |
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+------------+
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| 1 |
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| 3 |
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+------------+
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</pre>
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<p><strong>Explanation:</strong></p>
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<ul>
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<li>Alice (student_id 1) is a Computer Science major and has taken both Algorithms&nbsp;and Data Structures, receiving an A&nbsp;in both. She has also taken Machine Learning&nbsp;and Operating Systems&nbsp;as electives, receiving an A&nbsp;and B&nbsp;respectively.</li>
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<li>Bob (student_id 2) is a Computer Science major but did not receive an A&nbsp;in all required courses.</li>
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<li>Charlie (student_id 3) is a Mathematics major and has taken both Calculus&nbsp;and Linear Algebra, receiving an A&nbsp;in both. He has also taken Probability&nbsp;and Statistics&nbsp;as electives, receiving an A&nbsp;and B&nbsp;respectively.</li>
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<li>David (student_id 4) is a Mathematics major but did not receive an A&nbsp;in all required courses.</li>
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</ul>
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<p><strong>Note:</strong> Output table is ordered by student_id in ascending order.</p>
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</div>
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<!-- description:end -->
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## Solutions
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<!-- solution:start -->
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### Solution 1: Joining + Grouping + Conditional Filtering
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First, we calculate the average GPA of each student and store it in a temporary table `T`.
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Next, we join the `students` table with the `courses` table based on `major`, and then join with the `T` table based on `student_id`, followed by a left join with the `enrollments` table based on `student_id` and `course_id`.
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After that, we filter out students with an average GPA greater than or equal to 2.5, group by student ID, use the `HAVING` clause to filter students who meet the criteria, and finally sort by student ID.
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<!-- tabs:start -->
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#### MySQL
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```sql
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# Write your MySQL query statement below
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WITH
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T AS (
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SELECT student_id, AVG(GPA) AS avg_gpa
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FROM enrollments
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GROUP BY 1
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)
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SELECT student_id
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FROM
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students
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JOIN courses USING (major)
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JOIN T USING (student_id)
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LEFT JOIN enrollments USING (student_id, course_id)
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WHERE avg_gpa >= 2.5
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GROUP BY 1
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HAVING
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SUM(mandatory = 'yes' AND grade = 'A') = SUM(mandatory = 'yes')
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AND SUM(mandatory = 'no' AND grade IS NOT NULL) = SUM(mandatory = 'no' AND grade IN ('A', 'B'))
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AND SUM(mandatory = 'no' AND grade IS NOT NULL) >= 2
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ORDER BY 1;
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```
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<!-- tabs:end -->
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<!-- solution:end -->
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<!-- problem:end -->

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