Oracle DB link

create database link [custom database link] connect to

    [user] identified by [password] using

    '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=[hostname])

    (PORT=[port number]))(CONNECT_DATA=(SID=[ORACLE_SID])))';

create database link apps_prod connect to

    apps identified by apps using

    '(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=prod)

    (PORT=1521))(CONNECT_DATA=(SID=PROD)))';

select * from dba_db_links

select user_name from fnd_user@apps_prod