题解 | #统计作答次数#
统计作答次数
https://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
select
count(start_time) as total_pv,
count(submit_time) as complete_pv,
count(distinct if(submit_time is not null, exam_id, null)) as complete_exam_cnt
from exam_record
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