diff --git a/src/main/java/g3401_3500/s3421_find_students_who_improved/readme.md b/src/main/java/g3401_3500/s3421_find_students_who_improved/readme.md new file mode 100644 index 000000000..fce9ce00a --- /dev/null +++ b/src/main/java/g3401_3500/s3421_find_students_who_improved/readme.md @@ -0,0 +1,65 @@ +3421\. Find Students Who Improved + +Medium + +Table: `Scores` + + +-------------+---------+ + | Column Name | Type | + +-------------+---------+ + | student_id | int | + | subject | varchar | + | score | int | + | exam_date | varchar | + +-------------+---------+ + (student_id, subject, exam_date) is the primary key for this table. + Each row contains information about a student's score in a specific subject on a particular exam date. score is between 0 and 100 (inclusive). + +Write a solution to find the **students who have shown improvement**. A student is considered to have shown improvement if they meet **both** of these conditions: + +* Have taken exams in the **same subject** on at least two different dates +* Their **latest score** in that subject is **higher** than their **first score** + +Return _the result table_ _ordered by_ `student_id,` `subject` _in **ascending** order_. + +The result format is in the following example. + +**Example:** + +**Input:** + +Scores table: + + +------------+----------+-------+------------+ + | student_id | subject | score | exam_date | + +------------+----------+-------+------------+ + | 101 | Math | 70 | 15-01-2023 | + | 101 | Math | 85 | 15-02-2023 | + | 101 | Physics | 65 | 15-01-2023 | + | 101 | Physics | 60 | 15-02-2023 | + | 102 | Math | 80 | 15-01-2023 | + | 102 | Math | 85 | 15-02-2023 | + | 103 | Math | 90 | 15-01-2023 | + | 104 | Physics | 75 | 15-01-2023 | + | 104 | Physics | 85 | 15-02-2023 | + +------------+----------+-------+------------+ + +**Output:** + + +------------+----------+-------------+--------------+ + | student_id | subject | first_score | latest_score | + +------------+----------+-------------+--------------+ + | 101 | Math | 70 | 85 | + | 102 | Math | 80 | 85 | + | 104 | Physics | 75 | 85 | + +------------+----------+-------------+--------------+ + +**Explanation:** + +* Student 101 in Math: Improved from 70 to 85 +* Student 101 in Physics: No improvement (dropped from 65 to 60) +* Student 102 in Math: Improved from 80 to 85 +* Student 103 in Math: Only one exam, not eligible +* Student 104 in Physics: Improved from 75 to 85 + +Result table is ordered by student\_id, subject. \ No newline at end of file diff --git a/src/main/java/g3401_3500/s3421_find_students_who_improved/script.sql b/src/main/java/g3401_3500/s3421_find_students_who_improved/script.sql new file mode 100644 index 000000000..03c15b60b --- /dev/null +++ b/src/main/java/g3401_3500/s3421_find_students_who_improved/script.sql @@ -0,0 +1,16 @@ +# Write your MySQL query statement below +# #Medium #Database #2025_01_17_Time_466_ms_(74.56%)_Space_0B_(100.00%) + +WITH Ranked AS ( + SELECT + student_id, + subject, + FIRST_VALUE(score) OVER(PARTITION BY student_id,subject ORDER BY exam_date) AS first_score, + FIRST_VALUE(score) OVER(PARTITION BY student_id,subject ORDER BY exam_date DESC) AS latest_score + FROM Scores +) + +SELECT * FROM Ranked +WHERE first_score