题解 | #统计有未完成状态的试卷的未完成数和未完成率#
统计有未完成状态的试卷的未完成数和未完成率
https://www.nowcoder.com/practice/69fc2b1df4144c0991e4b8280d8aba27
select exam_id, sum(if(score is null,1,0)) as incomplete_cnt, round(sum(if (score is null,1,0))/count(exam_id),3) as incomplete_rate from exam_record group by exam_id having incomplete_cnt != 0
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