[LeetCode] 1280. Students and Examinations

 

 

[문제]

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[MySQL]

SELECT s.student_id
     , s.student_name
     , sub.subject_name
     , COUNT(e.student_id) AS attended_exams
FROM Students AS s
    CROSS JOIN Subjects AS sub
    LEFT JOIN Examinations AS e ON s.student_id = e.student_id
                                AND sub.subject_name = e.subject_name
GROUP BY s.student_id, sub.subject_name
ORDER BY s.student_id, sub.subject_name