--- In firebird-support@yahoogroups.com, "Adam" <s3057043@y...> wrote:

> > If I stop the Firebird Engine before the crash, I get the following
> > dataset result:
> >
> > COLUMN0, COLUMN1, SUM
> > 0, <null>, <null>
> > 0, <null>, <null>
> > 0, <null>, <null>
> > ....
> >
> >
> > Hundreds of similar rows.
> >
> > Is it a bug of Firebird?
> >
> > Thank you
>
> No it is a bug in your logic that assumes that NULL = NULL
>
> NULL does not equal NULL
> Therefore, every (0, NULL) combination would be considered unique.
>
> In fact I am not sure why
>
> select NULL, sum(*)
> from customers
> group by 1
>
> would work (although it does, logically it shouldn't). Perhaps that
> is a bug.
>
> Read this NULL guide for more info.
> http://www.ibphoenix.com/main.nfs?a=ibphoenix&page=ibp_firebird_null
>
> By the way it is possible to use first 1 syntax to stop it going to
> infinity, but still I would be looking for some other way of the
> wizard handling this.
>
> Hope that helps a little.
> Adam

Yes, I understand that A = B it's impossible to know if they are equal
if A and B are NULL, but "GROUP" groups the NULL values as 1 item
because all are unknonw.

For example:

select color, count(*) from product group by 1

it returns someting like:

<null>, 102
black, 23
white, 14


Note that all <null> are grouped in 1 item. It is right.

Now, if I do:

select 0, color, count(*) from product group by 1,2

the FB crashes and it is not ok, the result must be the same that the
first case plus a 0 column.