Create find-students-who-improved.sql

Author: kamyu104

MySQL/find-students-who-improved.sql

@@ -0,0 +1,20 @@
+# Time:  O(nlogn)
+# Space: O(n)
+
+# window function
+WITH score_cte 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 student_id,
+       subject,
+       first_score,
+       latest_score 
+FROM score_cte
+WHERE first_score < latest_score
+GROUP BY 1, 2
+ORDER BY 1, 2;