计算按列b分组的列a的sql百分比

Question

我的数据如下：

名称|颜色

joe | red  
joe | red
tom | blue  
joe | green  
tom | red  
mike | yellow  
mike | green  
mike | red

如何编写SQL以生成以下内容？

名称|颜色|百分比

joe | red | 66.6%
tom | blue | 50%
joe | green | 33.3%
tom | red | 50%
mike | yellow | 33.3%
mike | green | 33.3%
mike | red | 33.3%  

以下是我在微软访问SQL中尝试的代码

select name, color, (count(color)*100.0/count(*)) as 'perc'
from mytable
group by name, color;

Answer 1

您需要获取每种颜色的总数才能获得百分比。这需要加入另一个值。我认为以下内容适用于Access：

select nc.name, nc.color, nc.cnt * 100 / n.cnt & '%'
from (select name, color, count(*) as cnt
      from mytable as t 
      group by name, color
     ) as nc inner join
     (select name, count(*) as cnt
      from mytable as t
      group by name
     ) as n
     on nc.name = n.name;