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题解 | #统计作答次数#

select sum(case when start_time is not null then 1 end) ,sum(case when submit_time is not null and score is not null then 1 end) ,count(distinct case ...

Mysql

2021-11-13

0 238

题解 | #SQL类别高难度试卷得分的截断平均值#

select tb1.tag ,tb1.difficulty ,round(avg(tb1.score),1) from( select er.score ,ei.tag ,ei.difficulty ,row_number() over(order by er.score desc) r1 ,ro...

Mysql

2021-11-13

0 306