At 02:57 PM 30/03/2004 +0000, you wrote:

>Hello,
>
>I've got a small problem :
>
>I want to upgrade a Firebird database structure (change the size of a
>column: from 10 char to 13 char length)...
>For this I've tried a similar SQL instruction as we can write with
>Oracle...but this doesn't works...
>
>SQL > ALTER TABLE MYFBTABLE MODIFY (NAMEFIELD CHAR(13) NULL)
>
>It's seem that the error is the MODIFY instruction...

Yup.
ALTER TABLE MYFBTABLE
ALTER NAMEFIELD CHAR(13);

You can't change a non-nullable column into a nullable one.

btw, this question is off-topic here: post database and SQL questions to
firebird-support.

Helen