--如果不需要按照title分组求count
--查询前20天内顶数最高的20篇内容,倒序排列 
select top 20 title , [count] from tb where datediff(dd,addtime,getdate()) <= 20
order by [count] desc

--查询前20天内顶数最高的3篇内容,倒序排列 
select top 3 title , [count] from tb where datediff(dd,addtime,getdate()) <= 20
order by [count] desc

------解决方案--------------------

SQL code

select max(id) as id,CONVERT(varchar(10),[addtime],120)as [addtime],
 sum([count])  as [count] from [tbl]
where datediff(dd,[addtime],GETDATE())<=20
group by CONVERT(varchar(10),[addtime],120)
order by [count] desc