题解 | #统计作答次数#
统计作答次数
https://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
select
count(1) as total_pv,
count(submit_time) as complete_pv,
count(distinct if(submit_time and score is not null,exam_id,null)) as complete_exam_cnt
from
exam_record exam_record;
第三个语句很关键，题目要求的是完成的试卷数，要避免作答了而没有交卷的情况
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