整到一張表：

select 課程,

sum(人數*case 類別 when "優秀" then 1 else 0 end) 優秀人數,sum(人數*case 類別 when "優秀" then 1 else 0 end)/sum(人數)*100 優秀百分比，

sum(人數*case 類別 when "良好" then 1 else 0 end) 良好人數,sum(人數*case 類別 when "良好" then 1 else 0 end)/sum(人數)*100 良好百分比,

sum(人數*case 類別 when "中等" then 1 else 0 end) 中等人數,sum(人數*case 類別 when "中等" then 1 else 0 end)/sum(人數)*100 中等百分比,

sum(人數*case 類別 when "及格" then 1 else 0 end) 及格人數,sum(人數*case 類別 when "及格" then 1 else 0 end)/sum(人數)*100 及格百分比,

sum(人數*case 類別 when "缺考" then 1 else 0 end) 缺考人數,

sum(人數*case 類別 when "不及格" then 1 else 0 end) 不及格人數,

sum(人數*case when 類別 in("優秀","良好","中等","及格") then 1 else 0 end) 及格人數

from （select 課程,count(*) as 人數，‘優秀’ as 類別

from 成績

where grade>=90

group by 課程

union

select 課程,count(*) as 人數，‘良好’ as 類別

from 成績

where grade>80 and grade

group by 課程

union

select 課程,count(*) as 人數，‘中等" as 類別

from 成績

where grade>70 and grade

group by 課程

union

select 課程,count(*) as 人數，‘及格’ as 類別

from 成績

where grade>=60 and grade

group by 課程

union

select 課程,count(*) as 人數，‘不及格’ as 類別

from 成績

where grade

group by 課程

union

select 課程,count(*) as 人數，‘缺考" as 類別

from 成績

where grade is null

group by 課程）

group by 課程 ；