Multiple choice svar på T-SQL-forespørgsel

For hver spørgsmålsliste er de forventede svar og de indsendte svar (du skal bruge en FULL OUTER JOIN for at gøre dette, en LEFT deltage er ikke nok), og tæl antallet af kampe. Sammenlign derefter dette antal med antallet af de forventede svar.

select question_id, case when cnt = sum_test then 1 else 0 end as mark
from (
    select question_id, count(*) cnt, sum(test) sum_test
    from (
        select coalesce(q.question_id, s.question_id) as question_id, 
        correct_option_id, 
        submitted_option_id, 
        case when correct_option_id = submitted_option_id then 1 else 0 end as test
        from question_answer q full outer join user_exam_answer s 
        on q.question_id = s.question_id and q.correct_option_id = s.submitted_option_id
        ) x
    group by question_id
) y

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