106_students_and_examinations.md

SQL Everyday #106

Students and Examinations

Site: LeetCode
Difficulty per Site: Easy

Problem

Write a solution to find the number of times each student attended each exam.

Return the result table ordered by student_id and subject_name. [Full Description]

Submitted Solution

-- Submitted Solution
SELECT
    st.student_id
    ,st.student_name
    ,su.subject_name
    ,SUM(CASE WHEN ex.student_id IS NULL THEN 0 ELSE 1 END) AS attended_exams
FROM Students AS st
CROSS JOIN subjects AS su
LEFT JOIN Examinations AS ex ON st.student_id = ex.student_id
    AND su.subject_name = ex.subject_name
GROUP BY st.student_id, st.student_name, su.subject_name
ORDER BY st.student_id, su.subject_name
;

Site Solution

-- LeetCode Solution 
-- TO ADD

Notes

TODO

NB

TBD

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