Sql 如何在多个子记录集中查询不同的值
我正在使用SQLServer2008 下面是一个示例记录集 我想在每次更改时查询该值一次。例如,我想要第1、9、14、26、28、37和50行 我尝试过使用SELECT DISTINCT,但这不起作用,因为值列有重复的值,即第1行和第14行 我已经搜索了一段时间,没有找到解决方案。如果你有,请告诉我!谢谢Sql 如何在多个子记录集中查询不同的值,sql,sql-server,sql-server-2008,Sql,Sql Server,Sql Server 2008,我正在使用SQLServer2008 下面是一个示例记录集 我想在每次更改时查询该值一次。例如,我想要第1、9、14、26、28、37和50行 我尝试过使用SELECT DISTINCT,但这不起作用,因为值列有重复的值,即第1行和第14行 我已经搜索了一段时间,没有找到解决方案。如果你有,请告诉我!谢谢 Row Value Time Stamp 1 1916 2013-10-01 00:05:00 2 1916 2013-10-01 00:06:00 3 1916
Row Value Time Stamp
1 1916 2013-10-01 00:05:00
2 1916 2013-10-01 00:06:00
3 1916 2013-10-01 00:07:00
4 1916 2013-10-01 00:08:00
5 1916 2013-10-01 00:09:00
6 1916 2013-10-01 00:18:00
7 1916 2013-10-01 00:21:00
8 1916 2013-10-01 00:22:00
9 2272 2013-10-01 00:36:00
10 2272 2013-10-01 00:37:00
11 2272 2013-10-01 00:40:00
12 2272 2013-10-01 00:41:00
13 2272 2013-10-01 00:42:00
14 1916 2013-10-01 00:43:00
15 1916 2013-10-01 00:55:00
16 1916 2013-10-01 00:56:00
17 1916 2013-10-01 00:58:00
18 1916 2013-10-01 00:59:00
19 1916 2013-10-01 01:02:00
20 1916 2013-10-01 01:03:00
21 1916 2013-10-01 01:05:00
22 1916 2013-10-01 01:06:00
23 1916 2013-10-01 01:07:00
24 1916 2013-10-01 01:08:00
25 1916 2013-10-01 01:09:00
26 1860 2013-10-01 01:20:00
27 1860 2013-10-01 01:21:00
28 2272 2013-10-01 01:22:00
29 2272 2013-10-01 01:23:00
30 2272 2013-10-01 01:24:00
31 2272 2013-10-01 01:25:00
32 2272 2013-10-01 01:26:00
33 2272 2013-10-01 01:27:00
34 2272 2013-10-01 01:28:00
35 2272 2013-10-01 01:29:00
36 2272 2013-10-01 01:30:00
37 1917 2013-10-01 01:31:00
38 1917 2013-10-01 01:36:00
39 1917 2013-10-01 01:37:00
40 1917 2013-10-01 01:39:00
41 1917 2013-10-01 01:42:00
42 1917 2013-10-01 01:43:00
43 1917 2013-10-01 01:47:00
44 1917 2013-10-01 01:48:00
45 1917 2013-10-01 01:49:00
46 1917 2013-10-01 01:54:00
47 1917 2013-10-01 01:55:00
48 1917 2013-10-01 01:56:00
49 1917 2013-10-01 02:01:00
50 1860 2013-10-01 02:02:00
51 1860 2013-10-01 02:03:00
52 1860 2013-10-01 02:05:00
53 1860 2013-10-01 02:07:00
54 1860 2013-10-01 02:08:00
在最新版本的SQL Server中,可以使用lag函数。假设您有较旧的版本,则可以使用相关子查询:
select Value, TimeStamp
from (select t1.*,
(select top 1 value
from t t2
where t2.timestamp < t.timestamp
order by timestamp desc
) as prevvalue
from t t1
) t1
where prevvalue is null or prevvalue <> value;
在最新版本的SQL Server中,可以使用lag函数。假设您有较旧的版本,则可以使用相关子查询:
select Value, TimeStamp
from (select t1.*,
(select top 1 value
from t t2
where t2.timestamp < t.timestamp
order by timestamp desc
) as prevvalue
from t t1
) t1
where prevvalue is null or prevvalue <> value;
我显然还不能留下评论
where t2.timestamp < t.timestamp
应该是
where t2.timestamp < t1.timestamp
上面使用的是公共表表达式
;with cte as (select t1.*,
(select top 1 value
from table1 t2
where t2.timestamp < t1.timestamp
order by timestamp desc
) as prevvalue
from table1 t1
)
select Value, TimeStamp
from cte
where prevvalue is null
or prevvalue <> value
我显然还不能留下评论
where t2.timestamp < t.timestamp
应该是
where t2.timestamp < t1.timestamp
上面使用的是公共表表达式
;with cte as (select t1.*,
(select top 1 value
from table1 t2
where t2.timestamp < t1.timestamp
order by timestamp desc
) as prevvalue
from table1 t1
)
select Value, TimeStamp
from cte
where prevvalue is null
or prevvalue <> value
这只在2012年和更新版本的SQL Server中可用,但在2008年不可用…嗨,Gordon,我在实现这一点上遇到了困难。主要是因为为了获取上面发布的原始数据集,我已经使用了一个按[TimeStamp]按[TimeStamp]顺序按[TimeStamp]分区的行数作为num,以便每分钟仅获取1条记录。还有,有很多t。特别是,在t2.timestamp