SQL查询，我哪里错了？

Question

我正在尝试提取不同的 City 名称以及任何给定城市的唯一邮政编码。

zip city    state
00603   AGUADILLA   PR
00604   AGUADILLA   PR
00605   AGUADILLA   PR

查询：

SELECT DISTINCT (city),(zip) 
  FROM zips 
 WHERE state = 'PR'

我也尝试了 group by 子句，让我知道我错在哪里。

Answer 1

select city, max(zip)
from zips
where state='PR'
group by city

Answer 2

SELECT city, max(zip) from zips where state='PR' group by city, state