甲骨文，添加子查詢

Question

內查詢如下，工作正常獨立

select graduate.univid 
from graduate, projectmanager, university 
where graduate.empid = projectmanager.mgrid and rownum = 1 
group by graduate.univid 
order by count(graduate.univid) desc; 

但是當把作爲子查詢，ORACLE sqlplus中不斷給「缺少右括號」錯誤

select university.univname 
from university 
where exists 
(
select graduate.univid 
from graduate, projectmanager, university 
where graduate.empid = projectmanager.mgrid and rownum = 1 
group by graduate.univid 
order by count(graduate.univid) 
); 

時缺少右括號

我已經檢查了計算器類似的問題，但並不能真正幫助您使用

Answer 1

存在，所以你必須給大學和子查詢的條件。你錯過了你的錯誤我會猜對查詢：

select t1.univname 
from university t1 
where exists 
( select 1 from (
    select graduate.univid 
    from graduate, projectmanager, university 
    where graduate.empid = projectmanager.mgrid and rownum = 1 
    group by graduate.univid 
    order by count(graduate.univid)) t2 where t2.univid = t1.univid 
); 

Answer 2

假設你的邏輯是休息是正確的，問題是order by條款。您應該而不是在子查詢中使用它。 試試這個

select university.univname 
from university 
where exists 
(
select graduate.univid 
from graduate, projectmanager, university 
where graduate.empid = projectmanager.mgrid and rownum = 1 
group by graduate.univid 
); 

你可以自己嘗試一下。

這個查詢將返回1

select 1 from dual 
where exists 
(select 2 as id from dual) 

但是，這將失敗，併爲您ORA-00907: missing right parenthesis

select 1 from dual 
where exists 
(select 2 as id from dual order by id)