how to query between 2 remote databases

How to query on two tables that are on two different remote database with a join.

 s *
 f tb1_at_uid/pass_at_db1.world a, tb2_at_uid/pass_at_db2.world b  w a.col1 = b.col2

but this does not work, any idea ?

Thanks

-- 
Direct access to this group with http://web2news.com
http://web2news.com/?comp.databases.oracle.server