题解 | #统计作答次数#
统计作答次数
http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f
-- COUNT(column_name) 函数返回指定列的值的数目（NULL 不计入）：
SELECT COUNT(start_time) total_pv,
COUNT(submit_time) complete_pv,
(select count(distinct exam_id)
from exam_record
where submit_time is not null) complete_exam_cnt
FROM exam_record;
速腾聚创一面76人在聊