declare @t table (Date datetime,ID int,Content varchar(4))
insert into @t
select '2012-10-25',1,'test' union all
select '2012-10-26',1,'test' union all
select '2012-10-27',1,'test' union all
select '2012-10-28',1,'test' union all
select '2012-10-29',1,'test' union all
select '2012-11-15',1,'test' union all
select '2012-11-16',1,'test' union all
select '2012-11-17',1,'test' union all
select '2012-11-18',1,'test' union all
select '2012-12-11',2,'xx' union all
select '2012-12-12',2,'xx' union all
select '2012-12-13',2,'xx' union all
select '2012-12-14',2,'xx' union all
select '2012-2-1',3,'xxx' union all
select '2012-2-2',3,'xxx' union all
select '2012-2-3',3,'xxx' union all
select '2012-2-9',3,'xxx' union all
select '2012-2-10',3,'xxx' union all
select '2012-2-11',3,'xxx'
 
;with maco as
(
    select 
        row_number() over (order by (select 1)) as rid,
        Date,ID,[Content],cast(Date as int) as dint 
    from @t
)
select 
    convert(varchar(10),min(Date),120) as BeginDate,
    convert(varchar(10),max(Date),120) as EndDate,
    ID,[Content] 
from maco group by ID,[Content],dint-rid
/*
BeginDate  EndDate    ID          Content
---------- ---------- ----------- -------
2012-10-25 2012-10-29 1           test
2012-11-15 2012-11-18 1           test
2012-12-11 2012-12-14 2           xx
2012-02-01 2012-02-03 3           xxx
2012-02-09 2012-02-11 3           xxx
*/