I had some problems with the solution posted by Johannes, so I had to do some extra steps.
When trying to connect to oracle (step 4) by doing sqlplus / as sysdba I got:
ERROR: ORA-12560: TNS:protocol adapter error
The solution for this was executing the following line:
oradim -start -sid NEW_SID_NAME
Then connecting with / worked fine, but trying to connect to NEW_SID_NAME with system or HR got me another problem:
ERROR: ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
I checked that with the query select instance_name from v$instance;
that the listener would be NEW_SID_NAME, and so did. But running lsnrctl status
in the command line or querying select name from dba_services;
didn't show NEW_SID_NAME as a listener.
The solution of this problem was executing the followind sentence on sqlplus:
alter system set service_names='NEW_SID_NAME';
Maybe you'll need to execute alter system register;
after this also.
After doing this two steps I can connect to the NEW_SID_NAME with system and HR.
Hope it helps