Aime,
please help us help you by telling us a lot more about your problem.

>"arithmetic exception, numeric overflow, or string truncation error"

this error message occurs when dealing with too large numbers or too long
strings - e.g. if dividing by zero or adding two strings that are defined
pretty long (I am not certain whether they have to contain long data).

We would be much more helpful if you at least showed us your table
definitions and the actual SQL in question. Preferably also how you connect
(BDE, IBO, IBX or something else) and which versions you use of everything
(Interbase/Firebird on Windows/Linux etc).

HTH,
Set