如何将每10分钟之内的数据只显示一条(sql 2000)?
如何将每10分钟之内的数据只显示一条(sql 2000)?
一个表中有多条时间记录,要求按时间排序,相邻2条记录需要相差10分钟以上

create table a(dt datetime)

insert into a(dt)
select '2012-12-21 14:19'
union
select '2012-12-21 14:24'
union
select '2012-12-21 14:28'
union
select '2012-12-21 14:39'
union
select '2012-12-21 14:44'
union
select '2012-12-21 14:52'


需要的结果:
'2012-12-21 14:19'
'2012-12-21 14:39'
'2012-12-21 14:52'

或者查询出表中所有数据,将记录标识为是否有效,
(sql 2000版本 )

2012-12-21 14:19:00.000有效
2012-12-21 14:24:00.000无效
2012-12-21 14:28:00.000无效
2012-12-21 14:39:00.000有效
2012-12-21 14:44:00.000无效
2012-12-21 14:52:00.000有效

[解决办法]
这样写要简单点

DECLARE @minDt DATETIME
SET @minDt=(SELECT MIN(dt) FROM a)

SELECT MIN(dt) AS dt FROM a
GROUP BY DATEDIFF(mi,@minDt,dt)/10

[解决办法]

select a.dt,case isnull(b.dt,'12345') when '12345' then '无效' else '有效' end  from a left join
(
select dt from (
select DATEDIFF(mi,'1990-01-01 00:00:00',dt)/10 as dt from a)a
group by  dt having count(1)=1
)b on DATEDIFF(mi,'1990-01-01 00:00:00',a.dt)/10=b.dt

[解决办法]
--1
SELECT MIN(dt)
FROM (
SELECT dt , DATEDIFF (mi , (SELECT MIN (dt) FROM a) , a.dt)/ 10 AS d FROM a
) t
GROUP BY d


--2

SELECT a.dt ,CASE WHEN t.dt IS NULL THEN '无效' ELSE '有效' END
from
(
SELECT MIN(dt) AS dt
FROM (
SELECT dt , DATEDIFF (mi , (SELECT MIN (dt) FROM a) , a.dt)/ 10 AS d FROM a
) t
GROUP BY d
) t RIGHT JOIN a ON t.dt=a.dt