一条sql语句，间隔取数据

一条sql语句求救，间隔取数据
表中有一列为时间列
2011-08-03 19:25:27
2011-08-03 19:25:32
2011-08-03 19:25:37
2011-08-03 19:25:43
2011-08-03 19:25:48
2011-08-03 19:25:54
2011-08-03 19:25:59
2011-08-03 19:26:04
2011-08-03 19:26:10
2011-08-03 19:26:15
2011-08-03 19:26:20
2011-08-03 19:26:26
2011-08-03 19:26:31
2011-08-03 19:26:37
2011-08-03 19:26:43
2011-08-03 19:26:48
2011-08-03 19:26:53
2011-08-03 19:26:59
2011-08-03 19:27:04
2011-08-03 19:27:09
2011-08-03 19:27:15

现在想从这个表中取数据，不想显示这么多记录，只想显示每分钟的第一条记录就行。
比如上面的记录 只想显示为
2011-08-03 19:25:27
2011-08-03 19:26:04
2011-08-03 19:27:04


[解决办法]

SQL code

select * from tb t where col=(select max(col1) from tb where convert(varchar(16),col,120)=convert(varchar(16),t.col,120))
[解决办法]
SQL code
select * from tb awhere not exists (select 1 from tb b    where datediff(minute, a.dt, b.dt) = 0    and b.dt < a.dt)
[解决办法]
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
[解决办法]
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'