Re: Love or hate, or? domains with cardinality two

On Tue, 10 Nov 2015 19:01:06 +0100, Nicola <nvitacolonna_at_gmail.com> wrote:

>On 2015-11-09 23:33:52 +0000, Gene Wirchenko said:
>
>>> I was arguing about how schemas like that are commonly found in
>>> practice, and about how I feel uncomfortable with them, because, let
>>> apart the obvious difficulties with enforcing some integrity constraints
>>> (e.g., a department should have one and only one manager at a time) in
>>
>> Invalid assumption. I do some inventory counting and have seen
>> references in stores to co-managers. The store has more than one
>> store manager (not just managers of different ranks).
>
>And I have seen departments where the assumption (at least, the "only one"
>part) is valid. Anyway, the point is not whether the assumption is realistic
>or not, but what the implications are.

     It is important. If you use the wrong rules, you get a mess.

>> And what obvious difficulties?
>
>If you think there aren't any, show me a straightforward solution (of
>course, what is difficult and what is not is largely subjective!).

     I have not claimed that there were none.

     You are the one who made the claim that they were obvious. Prove your claim.

Sincerely,

Gene Wirchenko
o make the claim Received on Tue Nov 10 2015 - 19:21:54 CET