Oracle sql missing right parenthesis

Question

I'm trying to limit the number of rows that would be displayed when I run my query. When I run the code below in SQL developer, it returns missing right parenthesis error..

select * from
(select row_number()  over (order by rescode) rnum, a.* from
    (    
     SELECT * 
     FROM trans z 
     LEFT JOIN emails a 
     ON z.email1_hist_id=a.email_id 
     or z.email2_hist_id=a.email_id 
    ) a
)   where rnum between 1 and 50;

I tried running the inside query:

SELECT * 
FROM trans z 
LEFT JOIN emails a 
ON z.email1_hist_id=a.email_id 
or z.email2_hist_id=a.email_id

and it works fine. On the other hand I tried removing the OR portion of my query and included the limit rows query and it returns the number of rows I specified.

What exactly is wrong in my code?

Answer 1

This should work - you don't need two levels of subquery

select *
from
(    SELECT *, row_number()  over (order by rescode) rnum
     FROM trans z 
     LEFT JOIN emails a 
     ON (z.email1_hist_id=a.email_id or z.email2_hist_id=a.email_id)
) x
where rnum between 1 and 50;

Also, make sure there are no duplicate column names between trans and emails - this will trip the query because * from the inner query cannot return duplicate names.

Answer 2

我最好的猜测是，它不喜欢您给子选择一个别名，因此它在“）a”中的“ a”处引发了语法错误。

Answer 3

I don't recall about Oracle, but I know that MySQL actually requires sub-selections to have an alias. I'd try adding one to your outer sub-select (before the where rnum...).