UNION 无法将两个结果与同一列合并

Question

在这里输入图像描述我试图将这两个查询合并在同一个显示结果中，但是Mysql系统一直说UNION不能在这个位置。如果联合不起作用，我如何组合这两个查询？

Answer 1

https://dev.mysql.com/doc/refman /8.0/en/union.html 说：

就您而言，它看起来像这样：

(select customer_id, points, state from customers where state = 'CA' order by points desc limit 3)
union
(select customer_id, points, state from customers where state = 'FL' order by points desc limit 3)

您可能还想了解窗口函数：

select customer_id, points, state
from (
  select customer_id, points, state, 
    row_number() over (partition by state order by points desc) as rownum
  from customers where state in ('CA','FL')
) as t
where rownum <= 3