select convert(varchar(10),state_date,120) as date,
    sum(case when charge > 100 then 1 else 0 end) as cnt
from tb
group by convert(varchar(10),state_date,120)

------解决方案--------------------
SQL code
select state_date from tb
group by state_date
having sum(charge) >100
order by state_date

------解决方案--------------------
SQL code

select convert(varchar(10),state_date,120) as date,
    sum(case when charge > 100 then 1 else 0 end) as cnt
from tb
group by convert(varchar(10),state_date,120)
order by convert(varchar(10),state_date,120)

------解决方案--------------------
SQL code

--刚才是对原表数据存在的日期进行的统计，如果按时间段每天都显示，可以：

declare @start datetime
declare @end datetime
set @start = '2012-07-01'
set @end = '2012-07-10'
;with cte as
(
    select convert(varchar(10),dateadd(dd,number,@start),120) as date
    from master..spt_values
    where [type] = 'P' and number between 0 and datediff(dd,@start,@end)
)

select a.date,sum(case when isnull(b.charge,0)>100 then 1 else 0 end) as cnt
from cte a left join tb b on a.date = convert(varchar(10),b.state_date,120)
group by a.date