select
 * 
from
 tb t 
where
 col=(select max(col1) from tb where convert(varchar(16),col,120)=convert(varchar(16),t.col,120))

------解决方案--------------------
SQL code
select * from tb a
where not exists (select 1 from tb b
    where datediff(minute, a.dt, b.dt) = 0
    and b.dt < a.dt)

------解决方案--------------------
select a1.* from(
select row_number() over(partition by convert(varchar(100), datetimeObj, 23)+' '+convert(varchar(16),datepart(hh,datetimeObj))+':'+convert(varchar(16),datepart(mi,datetimeObj)) order by datetimeObj asc) as rowindex,* from table1) a1 where rowindex=1

注释：datetimeObj  表内时间字段名   table1 表名

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


    with cte as
    (
        select '2011-08-03 19:25:27' as v_time union all
        select '2011-08-03 19:25:32' union all
        select '2011-08-03 19:25:37' union all
        select '2011-08-03 19:25:43' union all
        select '2011-08-03 19:25:48' union all
        select '2011-08-03 19:25:54' union all
        select '2011-08-03 19:25:59' union all
        select '2011-08-03 19:26:04' union all
        select '2011-08-03 19:26:10' union all
        select '2011-08-03 19:26:15' union all
        select '2011-08-03 19:26:20' union all
        select '2011-08-03 19:26:26' union all
        select '2011-08-03 19:26:31' union all
        select '2011-08-03 19:26:37' union all
        select '2011-08-03 19:26:43' union all
        select '2011-08-03 19:26:48' union all
        select '2011-08-03 19:26:53' union all
        select '2011-08-03 19:26:59' union all
        select '2011-08-03 19:27:04' union all
        select '2011-08-03 19:27:09' union all
        select '2011-08-03 19:27:15' 
    ) ,
    cte2 as
    (
        select 
            v_time,
            ROW_NUMBER() over(partition by convert(varchar(16),v_time,120) order by v_time desc)  as v_rk
        from cte
    )    
    select * from cte2
    where v_rk='1'