题解 | #统计作答次数#
统计作答次数
http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
emm
SELECT
count(id) total_pv,
count(submit_time) complete_pv,
count(DISTINCT exam_id and submit_time is not null) complete_exam_cnt
FROM
exam_record;

