--- In ib-support@y..., Helen Borrie <helebor@d...> wrote:
> At 08:16 PM 16-05-01 +0000, you wrote:
>
> > Normally, due to app logic, reference constraints and before
insert
> >trigger on this table, it can't contain any 0's and nulls.
>
> I'd be interested to see the constraints you have defined to prevent
zero entries.

This table is container for last articles prices (from last invoice)
KODTOV is article's ID and improved by SCPR_FKNOM foreign key, SCTIP,
SCSTORE, SCNOMER is reference to invoice's primary (SCPR_FKSC foreign
key). Referenced tables have no zero entries. This table is filled
only by triggers from SC_POST (invoices). Other columns have no
relation to reference constraints.

>
>
> > Curious is null represented by 17-NOV-1858 00:00:00 in one of
date
> >columns and <null> in others... And I always thought null is
> >31-DEC-1899, but restore recognized it as null.
>
> No, you have some incorrect assumptions here.
> NULL is always NULL - "no value".
> If you enter zero in an InterBase date type , you will see
17-NOV-1858 00:00:00, which is date zero in IB.
>
> The date 31-DEC-1899 is date zero in Delphi, perhaps even in
Windows. Delphi doesn't admit the possiblity of nulls and replaces
them with zero (or empty string in the case of character fields).
>

Century live, century learn :)

> In any case, IB does not recognise either of these dates as NULL.

Maybe it was'nt IB but gbak. I had error restoring from .gbk with
message that DATEORD is null.

Best regards.