You have to check character set of your database or column. If you do
not specify it, it is "NONE" by default and will cause you problems
when working with unicode characters. There is no rule to translate
characters >0x80 between NONE and any other character set except
OCTETS.

- I've check the database and column encoding, it was set to
UNICODE_FSS. Should I use prepare statements to execute the query
instead of statement?

- Could you show me an example of using or perform the testing for
this case? i often test this case in web application using jsp page.

- on jsp page I add the syntax like this :
<%@ page contentType="text/html; charset=UTF-8"%> is it correct for
this case?

- about casting into OCTETS, could you show me an example of this?

Thanks,
Best Regards
wayan