SQLserver中对发票表（列有发票编码，发票日期，年份，订单号，供应商代码，产品代码，数量，单价，总额）进行按产品代码汇总总额，总额占比，计数，计数汇总
select 产品代码，sum(总额),count(*) as 计数 from 表
group by 产品代码
select 产品代码，产品总额,产品总额/总额 as 占比,计数
from
(select 产品代码，sum(总额) as 产品总额,count(*) as 计数 from 表
group by 产品代码) as g
left join (select sum(总额) as 总额 from 表) as t on 1=1