按类别选择行

Question

我需要按类选择一行，并且所选行必须是最低价格。

我有这样的：

结果必然是：

Answer 1

首先你需要得到每类的最低价格：

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

，然后为了增加这个r您需要将它们连接在一起：

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