如何统计周数据?

Question

select datediff(week,a,getdate()),min(a),sum(b)
from T
group by datediff(week,a,getdate())

Answer 1

--统计一年中的.
select 周数=datepart(week,a),b=sum(b) from t group by datepart(week,a)--分月统计的.
select 月份=convert(varchar(6),a,112)
  ,周数=datepart(week,a)-datepart(week,a-day(a))+1,
  ,b=sum(b)
from t
group by convert(varchar(6),a,112),datepart(week,a)-datepart(week,a-day(a))+1

Answer 2

select dateadd(day,-datepart(weekday,min(a))+2,min(a)) as 周一
      ,dateadd(day,8-datepart(weekday,min(a)),min(a)) as 周日
      ,sum(b)
from T
group by datediff(week,a,getdate())
order by min(a)