Urgent -How to save not latin dates?

[Ach]

Hi there,
Is there anybody knows how can I save not latin dates in Oracle? I mean for example: Jalali(shamsi) calender or Arabic Calender(Hijri) instead of using Julian Calendar.
Currently we do this by saving this dates in varchar type and another equivalent Latin datetime(e.g. 2 columns).We perform operations on Latin and then manipulate the varchar column and ofcourse application always will see this varchar column.
-Thanks alot

[jkoopmann]

Oracle stores date data types in their own internal format which i believe is an offset from some point in time.

anyway, To use a different calendar for display you need only set the NLS_CALENDAR environment variable. Also note that your O/S character set must be able to handle this display.

alter session set NLS_CALENDAR="Arabic Hijrah";

[Ach]

Thanks jkoopmann,
I want to do this in system level not in session level.This way I should not set it for every session,Am I right?
Is it possible to alter session set nls_calendar='Persian' using a trigger? Doesn't this beat the performance?
-Thanks for yout help

[jkoopmann]

yes you can set to Persian
yes you could use a logon trigger to do this.
if you want the setting for everyone then you should set in the init.ora parameter file as this is also a system setting.

[Ach]

Thanks Jemes,
I got the point.But when I tried to set nls_calendar parameter in init.ora and restart Oracle it does not start and says invalid parameter....
What shoud I do?

[jkoopmann]

Ach,
Sorry, Oracle documentation said both SESSION & SYSTEM modifiable but I just did another look at it is only SESSION modifiable.

SQL > select name,isses_modifiable,issys_modifiable from v$parameter where name = 'nls_calendar';

NAME                 ISSES ISSYS_MOD
-------------------- ----- ---------
nls_calendar         TRUE  FALSE

You would have to use a logon trigger or some other means.
here is a logon trigger if you need one to change.

CREATE OR REPLACE TRIGGER LOGON_TRIGGER
AFTER LOGON ON DATABASE
DECLARE
BEGIN
EXECUTE IMMEDIATE 'ALTER SESSION SET NLS_CALENDAR=''English Hijrah''';
END;
/