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    • main/java/g3601_3700/s3617_find_students_with_study_spiral_pattern
    • test/java/g3601_3700/s3617_find_students_with_study_spiral_pattern

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‎src/main/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/readme.md

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3617\. Find Students with Study Spiral Pattern
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Hard
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Table: `students`
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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 is the unique identifier for this table.
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Each row contains information about a student and their academic major.
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Table: `study_sessions`
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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 is the unique identifier for this table.
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Each row represents a study session by a student for a specific subject.
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Write a solution to find students who follow the **Study Spiral Pattern** - students who consistently study multiple subjects in a rotating cycle.
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* A Study Spiral Pattern means a student studies at least `3` **different subjects** in a repeating sequence
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* The pattern must repeat for **at least** `2` **complete cycles** (minimum `6` study sessions)
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* Sessions must be **consecutive dates** with no gaps longer than `2` days between sessions
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* Calculate the **cycle length** (number of different subjects in the pattern)
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* Calculate the **total study hours** across all sessions in the pattern
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* Only include students with cycle length of **at least** `3` **subjects**
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Return _the result table ordered by cycle length in **descending** order, then by total study hours in **descending** order_.
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The result format is in the following example.
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**Example:**
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**Input:**
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students table:
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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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study\_sessions table:
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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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**Output:**
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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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**Explanation:**
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* **Alice Chen (student\_id = 1):**
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* Study sequence: Math → Physics → Chemistry → Math → Physics → Chemistry
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* Pattern: 3 subjects (Math, Physics, Chemistry) repeating for 2 complete cycles
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* Consecutive dates: Oct 1-6 with no gaps > 2 days
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* Cycle length: 3 subjects
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* Total hours: 2.5 + 3.0 + 2.0 + 2.5 + 3.0 + 2.0 = 15.0 hours
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* **Bob Johnson (student\_id = 2):**
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* Study sequence: Algebra → Calculus → Statistics → Geometry → Algebra → Calculus → Statistics → Geometry
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* Pattern: 4 subjects (Algebra, Calculus, Statistics, Geometry) repeating for 2 complete cycles
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* Consecutive dates: Oct 1-8 with no gaps > 2 days
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* Cycle length: 4 subjects
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* Total hours: 4.0 + 3.5 + 2.5 + 3.0 + 4.0 + 3.5 + 2.5 + 3.0 = 26.0 hours
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* **Students not included:**
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* Carol Davis (student\_id = 3): Only 2 subjects (Biology, Chemistry) - doesn't meet minimum 3 subjects requirement
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* David Wilson (student\_id = 4): Only 2 study sessions with a 4-day gap - doesn't meet consecutive dates requirement
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* Emma Brown (student\_id = 5): No study sessions recorded
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The result table is ordered by cycle\_length in descending order, then by total\_study\_hours in descending order.

‎src/main/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/script.sql

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# Write your MySQL query statement below
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# #Hard #Database #2025_07_16_Time_553_ms_(100.00%)_Space_0.0_MB_(100.00%)
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-- WITH studentstudysummary AS (
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-- SELECT
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-- student_id,
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-- SUM(hours_studied) AS total_study_hours,
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-- COUNT(DISTINCT subject) AS cycle_length
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-- FROM
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-- study_sessions
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-- GROUP BY
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-- student_id
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-- HAVING
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-- COUNT(DISTINCT subject) >= 3
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-- ),
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-- rankedstudysessionswithgaps AS (
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-- SELECT
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-- ss.student_id,
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-- ss.subject,
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-- ss.session_date,
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-- DATEDIFF(
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-- LEAD(ss.session_date, 1, ss.session_date)
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-- OVER (PARTITION BY ss.student_id ORDER BY ss.session_date),
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-- ss.session_date
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-- ) AS gap_to_next_session,
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-- ROW_NUMBER() OVER (PARTITION BY ss.student_id ORDER BY ss.session_date) AS rn,
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-- sss.total_study_hours,
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-- sss.cycle_length
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-- FROM
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-- study_sessions ss
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-- INNER JOIN studentstudysummary sss
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-- ON ss.student_id = sss.student_id
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-- ),
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-- cyclicstudents AS (
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-- SELECT
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-- rss1.student_id,
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-- rss1.cycle_length,
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-- rss1.total_study_hours
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-- FROM
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-- rankedstudysessionswithgaps rss1
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-- INNER JOIN rankedstudysessionswithgaps rss2
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-- ON rss1.student_id = rss2.student_id
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-- AND rss2.rn = rss1.rn + rss1.cycle_length
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-- AND rss1.subject = rss2.subject
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-- WHERE
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-- rss1.gap_to_next_session < 3
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-- AND rss2.gap_to_next_session < 3
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-- GROUP BY
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-- rss1.student_id,
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-- rss1.cycle_length,
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-- rss1.total_study_hours
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-- HAVING
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-- COUNT(DISTINCT rss1.subject) >= 3
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-- )
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-- SELECT
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-- s.student_id,
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-- s.student_name,
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-- s.major,
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-- cs.cycle_length,
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-- cs.total_study_hours
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-- FROM
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-- cyclicstudents cs
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-- INNER JOIN students s
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-- ON cs.student_id = s.student_id
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-- ORDER BY
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-- cs.cycle_length DESC,
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-- cs.total_study_hours DESC;
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WITH studentstudysummary AS (
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SELECT
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student_id,
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SUM(hours_studied) AS total_study_hours,
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COUNT(DISTINCT subject) AS cycle_length
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FROM study_sessions
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GROUP BY student_id
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HAVING COUNT(DISTINCT subject) >= 3
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),
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rankedstudysessionswithgaps AS (
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SELECT
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ss.student_id,
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ss.subject,
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ss.session_date,
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DATEDIFF('DAY',
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ss.session_date,
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LEAD(ss.session_date, 1, ss.session_date) OVER (
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PARTITION BY ss.student_id ORDER BY ss.session_date
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)
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) AS gap_to_next_session,
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ROW_NUMBER() OVER (PARTITION BY ss.student_id ORDER BY ss.session_date) AS rn,
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sss.total_study_hours,
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sss.cycle_length
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FROM study_sessions ss
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INNER JOIN studentstudysummary sss
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ON ss.student_id = sss.student_id
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),
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cyclicstudents AS (
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SELECT
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rss1.student_id,
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rss1.cycle_length,
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rss1.total_study_hours
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FROM rankedstudysessionswithgaps rss1
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INNER JOIN rankedstudysessionswithgaps rss2
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ON rss1.student_id = rss2.student_id
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AND rss2.rn = rss1.rn + rss1.cycle_length
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AND rss1.subject = rss2.subject
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WHERE
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rss1.gap_to_next_session < 3
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AND rss2.gap_to_next_session < 3
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GROUP BY
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rss1.student_id,
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rss1.cycle_length,
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rss1.total_study_hours
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HAVING
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COUNT(DISTINCT rss1.subject) >= 3
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)
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SELECT
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s.student_id,
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s.student_name,
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s.major,
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cs.cycle_length,
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cs.total_study_hours
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FROM cyclicstudents cs
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INNER JOIN students s ON cs.student_id = s.student_id
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ORDER BY cs.cycle_length DESC, cs.total_study_hours DESC;

‎src/test/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/MysqlTest.java

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package g3601_3700.s3617_find_students_with_study_spiral_pattern;
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import static org.hamcrest.CoreMatchers.equalTo;
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import static org.hamcrest.MatcherAssert.assertThat;
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import java.io.BufferedReader;
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import java.io.FileNotFoundException;
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import java.io.FileReader;
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import java.sql.Connection;
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import java.sql.ResultSet;
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import java.sql.SQLException;
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import java.sql.Statement;
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import java.util.stream.Collectors;
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import javax.sql.DataSource;
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import org.junit.jupiter.api.Test;
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import org.zapodot.junit.db.annotations.EmbeddedDatabase;
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import org.zapodot.junit.db.annotations.EmbeddedDatabaseTest;
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import org.zapodot.junit.db.common.CompatibilityMode;
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@EmbeddedDatabaseTest(
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compatibilityMode = CompatibilityMode.MySQL,
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initialSqls =
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"CREATE TABLE students ("
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+ " student_id INT PRIMARY KEY,"
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+ " student_name VARCHAR(50),"
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+ " major VARCHAR(50)"
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+ ");"
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+ "INSERT INTO students (student_id, student_name, major) VALUES"
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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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+ "CREATE TABLE study_sessions ("
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+ " session_id INT PRIMARY KEY,"
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+ " student_id INT,"
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+ " subject VARCHAR(30),"
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+ " session_date DATE,"
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+ " hours_studied DECIMAL(3,1)"
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+ ");"
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+ "INSERT INTO study_sessions (session_id, student_id, "
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+ "subject, session_date, hours_studied) VALUES"
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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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class MysqlTest {
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@Test
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void testScript(@EmbeddedDatabase DataSource dataSource)
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throws SQLException, FileNotFoundException {
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try (final Connection connection = dataSource.getConnection()) {
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try (final Statement statement = connection.createStatement();
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final ResultSet resultSet =
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statement.executeQuery(
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new BufferedReader(
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new FileReader(
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"src/main/java/g3601_3700/"
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+ "s3617_find_students_with_"
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+ "study_spiral_pattern/"
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+ "script.sql"))
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.lines()
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.collect(Collectors.joining("\n"))
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.replaceAll("#.*?\\r?\\n", ""))) {
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assertThat(resultSet.next(), equalTo(true));
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assertThat(resultSet.getNString(1), equalTo("2"));
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assertThat(resultSet.getNString(2), equalTo("Bob Johnson"));
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assertThat(resultSet.getNString(3), equalTo("Mathematics"));
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assertThat(resultSet.getNString(4), equalTo("4"));
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assertThat(resultSet.getNString(5), equalTo("26.0"));
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assertThat(resultSet.next(), equalTo(true));
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assertThat(resultSet.getNString(1), equalTo("1"));
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assertThat(resultSet.getNString(2), equalTo("Alice Chen"));
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assertThat(resultSet.getNString(3), equalTo("Computer Science"));
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assertThat(resultSet.getNString(4), equalTo("3"));
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assertThat(resultSet.getNString(5), equalTo("15.0"));
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assertThat(resultSet.next(), equalTo(false));
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}
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}
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}
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}

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