First of all check if your database is capable to store Arabic characters by
SELECT *
from NLS_DATABASE_PARAMETERS
WHERE PARAMETER IN ('NLS_CHARACTERSET', 'NLS_NCHAR_CHARACTERSET');
If you get values like AL32UTF8
, AL16UTF16
or WE8ISO8859P6
you are fine and DB is able to store such characters.
In SQL Developer go to Tools / Preferences / Environment / Encoding and select UTF-8
.
Set an Environment Variable to NLS_LANG=ARABIC_AMERICA.AL32UTF8
or similar, you can also do NLS_LANG=.AL32UTF8
in order to keep default/existing language and territory. Alternatively you can set is also in your Registry at HKLM\SOFTWARE\Wow6432Node\ORACLE\KEY_%ORACLE_HOME_NAME%\NLS_LANG
(for 32 bit), resp. HKLM\SOFTWARE\ORACLE\KEY_%ORACLE_HOME_NAME%\NLS_LANG
(for 64 bit).
Then it should work.
Changing your local character set (i.e. NLS_LANG) does never affect any existing data in database.