Thank you Stefan for your help.

My connection set is not unicode, it's Windows-1250 due to specific-
national characters requirements. Unicode is a char representation in
application code, because it's written in Visual Studio 2005 C#.

I'll try to explain my application goal:

I have to implement this custom authentication scheme: user inputs
username and password, then my application calculates kind of hash
from password using particular password char manipulation (using char
ordinal value). Resulting string (set up of manipulated chars) is
sent to a stored procedure to authenticate with stored username and
kind-of hashed password in db.

That's why i have to cast int to char. Do you have any idea how to
avoid this, please? Thank you!

> you define the Client Character Set together with the connection. So
> even if your database is a Unicode database (character set

UNICODE_FSS

> in Firebird 1.5, which is UTF-8 on the database side) - when your
> client character set is a single byte character set like ISO8859_1

or

> WIN1252, you will not be able to pass Unicode characters to the
> database.