subqueries in from clause

Hi all,

I tried to make a query like this:

select * from COMPANY SELF
where exists
 (select PID from
   (select PID from PERSON where PID in
    (select PID from EMPLOYMENT where CID in
(select CID from COMPANY where CID = SELF.CID))))

(PID and CID are just some columns of the tables PERSON and COMPANY respectivly, EMPLOYMENT is an association table).

Even if it might seem a little bit crazy to write a query like that, I really need to do it that way. So,
I got the following error:

(select CID from COMPANY where CID = SELF.CID))))

*
ERROR at line 6:
ORA-00904: invalid column name

Does anyone know about restrictions in subqueries performed in the from clause of some query. I could not find any Information in the documentation.

Thanks for any help,

Sten

sl13_at_inf.tu-dresden.de Received on Tue Dec 19 2000 - 09:32:32 CST