> But the problem is that the RDB$TYPE_NAME and RDB$FIELD_LENGTH is
> quite different from what is shown in the Firebird GUI I use. There, it
> shows varchar, integer, etc and when I run the SQL Script it shows
> varying, long, text, int64, etc.
>
> So, does anyone knows how to convert these types shown when i run
> the SQL Script to the types shown in the Firebird GUI?

Yes, use CASE expression.

SELECT
CASE RDB$FIELD_TYPE WHEN 8 THEN 'INTEGER' WHEN 37 THEN 'VARCHAR' ... END

Ivan