易错点:两表格连接,where条件与on条件混淆 select grade.* from( #对成绩按科目进行排序 select grade.id,grade.job,grade.score,ROW_NUMBER()over(partition by job order by score desc) as t_rank from grade) grade left join (select a.job,round(if(mod(c,2)<>0,(c+1)/2,c/2),0) as start, round(if(mod(c,2)<>0,(c+1)/2,c/2+1),...