题解 | #统计作答次数#
统计作答次数
http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
根据不同的exam_id,score不为空查询
select
count(id) as total_pv,
count(score) as complete_pv,
count(distinct exam_id and score IS NOT NULL) as complete_exam_cnt
from exam_record
