我有一个表是这样的。
time Sample SampleValue
2007-4-5 13:00 Ph值 4
2007-4-5 13:01 Ph值 5
2007-4-5 13:02 Ph值 6
2007-4-5 13:00 COD值 4
2007-4-5 12:59 Ph值 4
2007-4-5 13:04 COD值 4
2007-4-5 13:10 COD值 4
2007-4-5 13:25 A 4
2007-4-5 13:16 B 4
2007-4-5 13:27 B 4怎么写一条语句,将各个Sample的最大时间的那条记录选出来。
变成:
time Sample SampleValue
2007-4-5 13:27 B 4
2007-4-5 13:25 A 4
2007-4-5 13:10 COD值 4
2007-4-5 13:02 Ph值 6
这样呢?
time Sample SampleValue
2007-4-5 13:00 Ph值 4
2007-4-5 13:01 Ph值 5
2007-4-5 13:02 Ph值 6
2007-4-5 13:00 COD值 4
2007-4-5 12:59 Ph值 4
2007-4-5 13:04 COD值 4
2007-4-5 13:10 COD值 4
2007-4-5 13:25 A 4
2007-4-5 13:16 B 4
2007-4-5 13:27 B 4怎么写一条语句,将各个Sample的最大时间的那条记录选出来。
变成:
time Sample SampleValue
2007-4-5 13:27 B 4
2007-4-5 13:25 A 4
2007-4-5 13:10 COD值 4
2007-4-5 13:02 Ph值 6
这样呢?
inner join (select max(time) as time,Sample from 表 group by Sample)t on a.time=t.time and a.Sample=t.Sample
from table01 inner join
(select max(time) as time ,Sample from table01 group by Sample) b
on table01.time=b.time and table01.Sample=b.Sample
inner join (
select max(time) as time,Sample from table group by Sample ) b on a.time=b.time and a.Sample=b.Sample