我如何仅按字母顺序在SQL查询中保留1个结果？

Question

该问题询问的是每个国家的商品总值最高的城市。基本上，有些城市的商品数量相同，但我们只按字母顺序保留第一个。结果仅包含国家/地区名称，商品数量最多的城市及其商品总数。

我的查询结果：

France            Paris        85
Germany           Berlin       100
Germany           Frankfurt    100
Germany           Luxembourg   100
Netherlands       Amsterdam    75
Spain             Barcelona    93

正确的结果应该是：

France            Paris        85
Germany           Berlin       100
Netherlands       Amsterdam    75
Spain             Barcelona    93

Answer 1

将聚合函数min()用于城市，将max()用于no_of_goods。

select country, min(city) as city, max(no_of_goods) as no_of_goods from tableA
group by country

Answer 2

您可以使用row_number()：

select t.*
from (select t.*, row_number() over (partition by country order by city) as seq,
             max(no_goods) over (partition by country) as max_good
      from table t
     ) t
where seq = 1;