>> Is there a way to prevent a Insert, if a unique column contains the
>> same word which is to insert but only in upper chars ?
>
> Add another column, a varchar of the same size, and place the unique index on it, not on the mixed case column.
>
> Have a Before Insert trigger to populate the "case insensitive" column:
>
> as
> if (new.MixedCaseColumn is not null) then
> new.CaseInsensitiveColumn = UPPER(new.MixedCaseColumn);
>
> Of course, if MixedCaseColumn is non-nullable, the null test isn't required.

Just a note. In Firebird 2.x, one could create an UNIQUE expression
index with UPPER on the field in question.



--
Best Regards,
Thomas Steinmaurer
LogManager Series - Logging/Auditing Suites supporting
InterBase, Firebird, Advantage Database, MS SQL Server and
NexusDB V2
Upscene Productions
http://www.upscene.com