試圖通過SQL查詢來找到一組最小值

Question

我非常近有與此查詢（SQL Server 2008 R2中）：

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

輸出：

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

我只需要在稱爲kfactor的另一列中添加最大值。

此列中每個組都有數百個值，我無法在上述查詢中爲每個組列出單個值。

Answer 1

我想你只需要添加max()函數。

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