UNICODE in mysql error

[vis good in mysql someday]

"INSERT INTO User "
"(UnicodeName,...) VALUES ( "+'UUUUU'+"....)";

UnicodeName is an unique field.
here 'UUUUU' stands for 5 unicode characters (10 bytes) - because I can not display uncode characters on the forum.

if 'UUUUU' doesn't exist in table User, the SQL is successfully executed.

my problem is:
if 'UUUUU' exists already,
const char*p=::mysql_error(pmy_Init); //pmy_init is a pointer to st_mysql)
returns error:

Duplicate entry 'MQ9?' for key 'UnicodeName'.

meaning of the error string is clear, but 'MQ9?' is not 'UUUUU' -- I guess the error string mixes with english and unicode characters, problem is that function mysql_error(...) doesn't catch error in unicode, so, the error string on unicode part is displayed incorrectly.

How to get an unicode error string to indicate 'UUUUU' correctly?

(OS: Windows, using MFC)