题解 | #统计作答次数#

统计作答次数

http://www.nowcoder.com/practice/45a87639110841b6950ef6a12d20175f

sum+if或者sum+case when yyds!!

select count(*) as total_pv
,count(submit_time) as complete_pv
,count(distinct case when submit_time is not null and score is not null then exam_id end) as complete_exam_cnt
from exam_record
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