根据值获取唯一行并按时间排序

Question

我有下表。我希望按时间（asc）获得每个源顺序中的1个。来源不固定 - 它可以是任何东西

Time                    |Source
------------------------------------
2012-08-18 05:00:03.000 | A
2012-08-19 06:00:03.000 | B
2012-08-18 06:00:03.000 | B
2012-08-20 06:00:03.000 | C
2012-08-21 06:00:03.000 | A

基于上面的表格得到以下结果

Time                    |Source
------------------------------------
2012-08-18 05:00:03.000 | A
2012-08-18 06:00:03.000 | B
2012-08-20 06:00:03.000 | C

Answer 1

您想要使用MIN()聚合函数和GROUP BY源代码值。所以我相信这会做你想要的。 （见SQL Fiddle with Demo）

select min([time]) minTime, source
from yourTable
group by source
order by minTime

Answer 2

select id, source, min(time) t 
from table 
group by source, id
order by t