Student Scores by Course

Table with columns student_id, course_id, exam_score: list students whose score in every course is above that course's average score. Asked in the First interview stage. Candidate answered with a join to per-course averages and a tag flag. Write a SQL query using the exam_scores table.

Output

1. Return one row per qualifying student.
2. Include the column student_id only.
3. Include students whose score is strictly above the average for every course they have taken. A NULL score does not qualify.
4. Order by student_id ascending.