Re: Do we always have to update or insert? Why can't we just relate?

Gene Wirchenko wrote:
> On 17 Oct 2005 16:28:22 -0700, "JOG" <jog_at_cs.nott.ac.uk> wrote:
>
> >Given two sets {2, 3, 4} and {3, 4, 5}, if I wanted to perform a union
> >upon them, I would expect to get the result {2, 3, 4, 5} and not an
> >error message stating the 3 and 4 existed in both. Is this analagous to
> >an insert? If this is the case, with an insert viewed as the union of
> >the relation's existing set of elements with specified insert set
> >(which just contains a single element), then from a purely theoretical
> >standpoint an error message does seem suprising.
>
> Good point on theory, but the inserts are one-at-a-time, so the
> analogy is not strong.

What about bulk inserts?

> My preference is that each action that I choose to do gets an
> appropriate response. If I am adding one row to a table, then
> another, then another, that is three actions, each with their own
> response. If my action is performing the union of two sets, then I
> expect the result you give above.

Consider what happens when you delete a row: if you delete where primary key = xxx, that will necessarily affect at most one row. If there aren't any qualifying rows, that's not an error. It doesn't seem symmetric.

> I can see that this is YMMV.

Yeah, I think that's true.

Marshall Received on Tue Oct 18 2005 - 02:08:47 CEST