在 oracle 11 的子查詢中使用 rownum

Question

我有這樣的查詢。它在 oracle 12 上正常工作。

select * from customers where customerId IN (select custId from Orders where 
   orderStatus = 'S' and orderCity = 'Amsterdam' and ORDER BY custId DESC FETCH FIRST 10 ROWS ONLY)

但我正在使用 oracle 11.該查詢不適用於 oracle 11.因此我改變了我的查詢

select * from customers where customerId IN (select custId from Orders where 
  orderStatus = 'S' and orderCity = 'Amsterdam' and ORDER BY custId DESC rownum <= 10)

它給出了missing right paranthesis

我該如何解決這個問題。你有什么想法嗎？實際上我在 10 數字上使用了一個變量。

Answer 1

語法有點不同 - 您需要一個額外的子查詢，因此它需要更像... where customerId IN (select * from (select custId from Orders where orderStatus = 'S' and orderCity = 'Amsterdam' and ORDER BY custId DESC) where rownum <=10)

如果您沒有 order by 子句，則不需要額外的子查詢

For ref see https://docs.oracle.com/cd/B19306_01/server.102/b14200/pseudocolumns009.htm#:~:text=For%20each%20row%20returned%20by,has%202%2C%20and% 20so%20on 。

Answer 2

我會用exists和row_number()來表達這個：

select c.* 
from customers 
where exists (
    select 1
    from (
        select custId, row_number() over(order by custid desc) rn
        from orders 
        where orderStatus = 'S' and orderCity = 'Amsterdam'
    ) o
    where o.rn <= 10 and o.cusid = c.customerid
)

row_number()在子查詢中按客戶 ID 降序排列訂單。 然后，我們過濾前 10 行，並使用exists過濾外部查詢中的相應行。