题解 | #统计作答次数#
统计作答次数
https://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
select count(*) as total_pv, sum(if(score is not null, 1, 0)) as coplete_pv, (select count(*) from (select exam_id from exam_record where score is not null group by exam_id) as new) as complete_exam_cnt from exam_record;