select * from dbo.Tab_Article where ADate between '2009-09-14' and '2009-09-14'

declare @sdt datetime ,@edt datetime
set @sdt='2009-09-14'
set @edt='2009-09-14'
select 精确毫秒=dateadd(ms,-1,dateadd(dd,1,@edt)),精确到秒=dateadd(ss,-1,dateadd(dd,1,@edt))

/*
精确毫秒                                                   精确到秒                                                   
------------------------------------------------------ ------------------------------------------------------ 
2009-09-15 00:00:00.000                                2009-09-14 23:59:59.000

（所影响的行数为 1 行）

*/

--所以只能精确到秒，修改如下

select * from dbo.Tab_Article where ADate between @sdt and dateadd(ss,-1,dateadd(dd,1,@edt)

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

if object_id('tb') is not  null
  drop table tb

create table tb(dt datetime)
insert tb
select '2009-10-20 12:52:52' union all
select '2009-10-20 00:00:00' union all
select '2009-10-20 23:59:59' union all
select '2009-10-21 00:00:00' union all
select '2009-10-21 12:52:52'

select * from tb where dt>='2009-10-20' and dt<'2009-10-21'
/*
2009-10-20 12:52:52.000
2009-10-20 00:00:00.000
2009-10-20 23:59:59.000
*/

select * from tb where dt between '2009-10-20' and '2009-10-21'
/*
2009-10-20 12:52:52.000
2009-10-20 00:00:00.000
2009-10-20 23:59:59.000
2009-10-21 00:00:00.000
*/

------解决方案--------------------
select * from dbo.Tab_Article where ADate between @startdate and dateadd(day,1,@enddate)


------解决方案--------------------
select * from dbo.Tab_Article where ADate between '2009-09-14' and '2009-09-14'
select * from dbo.Tab_Article where ‘2009-09-14 00：00：00 ’《=ADate《=’2009-09-14：23：59：59'