UNION 無法將兩個結果與同一列合併

Question

在這裡輸入圖像描述我試著將這兩個查詢合併在同一個顯示結果中，但Mysql系統一直說UNION不能在這個位置。如果聯合不起作用，我該如何組合這兩個查詢？

Answer 1

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

就您而言，它看起來像這樣：

(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)

您可能還想了解視窗函數：

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