题解 | #统计作答次数#
统计作答次数
http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
select count(start_time) as total_pv,
COUNT(submit_time) as complete_pv,
#去除未完成的试卷
COUNT(distinct exam_id and score is not null) as complete_exam_cnt
from
exam_record;
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