题解 | #统计作答次数#
统计作答次数
http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
select count(id) as total_pv ,count(case when submit_time is not null then id end) as complete_pv ,count(distinct case when submit_time is not null then exam_id end) as complete_exam_cnt from exam_record