尝试通过SQL查询从组中查找最小值

Question

我非常接近这个查询（SQL Server 2008 R2）：

Select selectedicao, selectedyear, selectedmonth
From weatherdaily
Where Selectedyear = 1990 and selectedmonth = 1
Group By selectedicao, selectedyear, selectedmonth

输出：

selectedicao    selectedyear    selectedmonth
-------------------------------------------------
KPKB            1990            1
KORD            1990            1
KFWA            1990            1
KCDW            1990            1
KFDY            1990            1
KLCK            1990            1

我只需要在另一个名为kfactor的列中添加Max值。

此列为每个组都有数百个值，我无法在上述查询中为每个组列出单个值。

Answer 1

我认为您只需要添加max()功能。

Select selectedicao, selectedyear, selectedmonth, max(kfactor) as max_kfactor
From weatherdaily
Where Selectedyear = 1990 and selectedmonth = 1
Group By selectedicao, selectedyear, selectedmonth