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(score != '(NULL)') as complete_pv, complete_exam_cnt from exam_record join (select count(distinct exam_id) complete_exam_cnt from exam_record where score != '(NULL)') as t1 on 1 group by complete_exam_cnt
把试卷数单独统计
