Interesting Which privs has been assigned to the said user On 7 Jul 2011 19:53, "Niall Litchfield" <niall.litchfield@xxxxxxxxx> wrote: Someone, somewhere asked me if users connecting to a database using SID in the tnsnames file actually got connected to the SYS$USERS service. I have lost my note of where I was asked this, but oracle-l seems likely. The answer is (at least in 11.2 on Windows) yes. I apologize if this is meaningless to everyone. In the output below SID is my sql prom tnsalias with SID specified in connect descriptor - niall is the service_name variant. I've only edited the output for domain name. SQL >conn niall/niall@sid NIALL @ sid >select service_name from v$session where sid = (select sid from v$mystat where rownum = 1); SERVICE_NAME ---------------------------------------------------------------- SYS$USERS NIALL @ sid >conn niall/niall@niall Connected. NIALL @ niall >select service_name from v$session where sid = (select sid from v$mystat where rownum = 1); SERVICE_NAME ---------------------------------------------------------------- niall.domain.name -- Niall Litchfield Oracle DBA http://www.orawin.info