At 08:13 AM 27/08/2003 +0000, you wrote:

>Hi
>
>I have a table (FB 1.5 RC4) where a timestamp field with
>default 'now' value shows always current time (or sometimes a time
>little bit in the past) in some rows. When I requery data, the time
>is new. It is NOT defined as a computed field.
>
>currently the table looks like this:
>CREATE TABLE "CULLING_REASONS"
>(
> "CODE" NUMERIC(2, 0) NOT NULL,
> "DESCRIPTION" VARCHAR(50) NOT NULL,
> "CHANGE_DT" TIMESTAMP default 'now' NOT NULL,
> PRIMARY KEY ("CODE")
>);
>
>But at first I didn't created it that way. First it didn't
>have "default" on "change_dt" field . I inserted data and later
>added "default" with a tool that probably tweaked system tables
>directly. (I don't remember if the "not null" was also added later
>along with "default", probably not) And now the "change_dt" keeps
>showing always current time. I updated the value on some rows and
>then the value remained fixed on those rows.
>
>I have no proble with that (if I update and fix those strange
>fields), just thought someone might be interested that such behaviour
>can happen. Unfourtunately I don't remember exactly how that table
>structure evolved, maybe my explanation leads to wrong path.

You don't understand what DEFAULT is intended to do. It is written only
once - at INSERT time - and then ONLY if the column is not included in the
field-list.

If you want this timestamping capability, that you mistakenly expected to
get from your DEFAULT constraint, you need to write BEFORE INSERT and
BEFORE UPDATE triggers to do it.

heLen