我有一个包含以下架构的表:
CREATE TABLE Sales (
"Date" date,
ID char(3),
Volume integer not null check (Volume >= 0),
primary key ("Date", ID)
;
日期是产品销售的日期,ID是产品的ID,Volume是当天销售的产品数量。这是插入数据库的示例数据:
Date | ID | volume
------------+------+---------
2012-01-03 | AAA | 100
2012-01-03 | BBB | 50
2012-01-03 | CCC | 356
2012-01-04 | AAA | 66
2012-01-04 | CCC | 99
2012-01-15 | BBB | 210
我想查看每天销售量最大的产品。
预期产量如下:
Date | ID | volume
------------+------+---------
2012-01-03 | CCC | 356
2012-01-04 | CCC | 99
2012-01-15 | BBB | 210
我尝试了以下代码,但它输出错误:
create or replace view Sales("Date", ID, volume) as
select a."Date", a.ID, max(a.volume)
from Sales a
group by a."Date", a.ID
;
我觉得组a.ID部分有问题,但我不确定。非常感谢任何帮助,谢谢!
第一组按日期获取最大卷,然后加入表以获取与每个最大卷对应的行:
select s.*
from sales s inner join (
select "Date", max(Volume) maxVolume
from sales
group by "Date"
) g on g."Date" = s."Date" and g.maxVolume = s.Volume
order by s."Date"