By changing NLS_LANG you would not help yourself to support all those languages if your character set is default us7ascii.
Do select * from nls_database_parameters;
look for NLS_CHARACTERSET and if it is US7ASCII or anything else but UTF8 you can not support FRENCH, CHINESE, ENGLISH together in one database.
If you are on oracle 8i and your database's character set is us7ascii you can follow instructions from NLS Support Guide on using ALTER DATABASE SET CHARACTERSET command to move from us7ascii to UTF8. If you are not on Oracle 8i and/or your characater set is not us7ascii, you have to rebuild database to move from your current character set to UTF8. But I suggest you read first if you need to have a database that supports all those languages. Two many options and you may make a wrong decision :-)
Alla S. Pfauntsch
"Life is what happens while you are planning something else".
Thanx..my db is on oracle8i (8.1.5) on Sun. I just wanted the info before creating my database. We were just trying out the possibilities.
Would be grateful if you could provide some more info on the same.