SQL & PL/SQL

I am following along in the first Sybex OCA book with Oracle 9i Personal Edition using version 9.2.0...(I believe 9.2.0.0.1?)

I am using the seed database that contains hr and various others...I got to the following command, but under the hr login, it says I do not have permission. So I tried logging in as system and it claims ORA-02231: missing or invalid option to ALTER DATABASE. The same occurs if I login under sys AS sysdba (or as sysoper) or if I login under system AS sysdba.

I tried the command (which I no longer remember) to export the init.oca settings (it created INITorcl.OCA or initORCL.oca) as one message indicated it might be the compatibility setting. However that was set to 9.2.0 and the message said it needed to be 9.1 or higher.

What am I doing wrong?

It is on P. 142, Chapter 3 (single-Row Fucntions) and the command is simple enough...
ALTER DATABASE SET TIME_ZONE='-06:00';
(and it should reply database altered)
I have also tried ALTER DATABASE SET TIME_ZONE='US/Central'; and many, many other variances. Ideally, after that succeds one should do a
SHUTDOWN
STARTUP
and then be able to SELECT DBTIMEZONE FROM dual; to get a dbtime of -06:00, but since it thinks my assignment is invalid, I cannot find a way to get it to accept it. Plz help. I have been searching extensively and trying numerous ideas. While I know it is of little importance now, I want to understand every aspect I can.


This is the book by Chip Dawes and Biju Thomas (OCA/OCP: Introduction to Oracle9i SQL Study Guide)

Thanks,
Ross