按類別選擇行

Question

我需要按類選擇一行，並且所選行必須是最低價格。

我有這樣的：

結果必然是：

Answer 1

首先你需要得到每類的最低價格：

select Class, min(price) as minimum from myTable group by Class 

，然後爲了增加這個r您需要將它們連接在一起：

select b.* from (
    select Class, min(price) as minimum from myTable group by Class 
) as a inner join myTable as b on a.class = b.class and a.minimum = b.price