Find The Quiet Students In All Exams Problem
Description
LeetCode Problem 1412.
Table: Student
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+---------------------+---------+
| Column Name | Type |
+---------------------+---------+
| student_id | int |
| student_name | varchar |
+---------------------+---------+
student_id is the primary key for this table.
student_name is the name of the student.
Table: Exam
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+---------------+---------+
| Column Name | Type |
+---------------+---------+
| exam_id | int |
| student_id | int |
| score | int |
+---------------+---------+
(exam_id, student_id) is the primary key for this table.
Student with student_id got score points in exam with id exam_id.
A “quite” student is the one who took at least one exam and didn’t score neither the high score nor the low score.
Write an SQL query to report the students (student_id, student_name) being “quiet” in ALL exams.
Don’t return the student who has never taken any exam. Return the result table ordered by student_id.
The query result format is in the following example.
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Student table:
+-------------+---------------+
| student_id | student_name |
+-------------+---------------+
| 1 | Daniel |
| 2 | Jade |
| 3 | Stella |
| 4 | Jonathan |
| 5 | Will |
+-------------+---------------+
Exam table:
+------------+--------------+-----------+
| exam_id | student_id | score |
+------------+--------------+-----------+
| 10 | 1 | 70 |
| 10 | 2 | 80 |
| 10 | 3 | 90 |
| 20 | 1 | 80 |
| 30 | 1 | 70 |
| 30 | 3 | 80 |
| 30 | 4 | 90 |
| 40 | 1 | 60 |
| 40 | 2 | 70 |
| 40 | 4 | 80 |
+------------+--------------+-----------+
Result table:
+-------------+---------------+
| student_id | student_name |
+-------------+---------------+
| 2 | Jade |
+-------------+---------------+
For exam 1: Student 1 and 3 hold the lowest and high score respectively.
For exam 2: Student 1 hold both highest and lowest score.
For exam 3 and 4: Studnet 1 and 4 hold the lowest and high score respectively.
Student 2 and 5 have never got the highest or lowest in any of the exam.
Since student 5 is not taking any exam, he is excluded from the result.
So, we only return the information of Student 2.
MySQL Solution
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select student_id,student_name
from student
where student_id in (select student_id from exam) and
student_id not in
(select student_id
from
(select student_id,
rank() over(partition by exam_id order by score asc) as asc_rank,
rank() over(partition by exam_id order by score desc) as desc_rank
from exam) tab1
where asc_rank=1 or desc_rank=1)
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