select * from (select a.c#,cname,case when score>=85 then ‘100-85‘                         when score<85 and score>=70 then ‘85-70‘                         when score<70 and score>=60 then ‘70-60‘                         else ‘0-60‘                         end 段位                          ,count(1) 数量             ,count(1)*100.0/(select count(1)from sc where c#=a.c#) 均分from sc a join course b on a.c#=b.c#group by a.c#,cname,case when score>=85 then ‘100-85‘                         when score<85 and score>=70 then ‘85-70‘                         when score<70 and score>=60 then ‘70-60‘                         else ‘0-60‘                         end) aorder by  a.c#, case 段位                        when  ‘0-60‘ then 1                       when  ‘70-60‘ then 2                           when  ‘85-70‘ then 3                           when  ‘100-85‘ then 4                              end