Re: boolean datatype ... wtf?
Date: Wed, 06 Oct 2010 17:25:37 -0300
Message-ID: <4cacdb42$0$14810$9a566e8b_at_news.aliant.net>
paul c wrote:
> On 06/10/2010 11:03 AM, Bob Badour wrote:
>
>> paul c wrote:
>>
>>> On 06/10/2010 6:51 AM, Bob Badour wrote:
>>>
>>>> Null is an indicator that evaluates to NULL or NOT NULL. ie. it is a
>>>> boolean.
>>>
>>> This makes me want to take another stab at an old point. I think it is
>>> a boolean and how it's constructed within a relational db seems
>>> crucial which I'd say it can't be in any logical way. Maybe this is
>>> part of what what Erwin S means too.
>>>
>>> It's reminiscent of how Table_Dee has a maximum cardinality of one,
>>
>> You misspoke. Table_Dee has a cardinality of exactly one. Table_Dum has
>> a cardinality of exactly zero. Nilary relations have a maximum
>> cardinality of one and a minimum cardinality of zero.
>
> yes, the word 'maximum' here was pointless, albeit not untrue. What is
> a 'nilary' relation, don't remember that term, is it one with no
> attributes?
Yes. Nilary (perhaps more common as nullary?) is to unary as unary is to binary and as binary is to ternary.
http://en.wikipedia.org/wiki/Arity Received on Wed Oct 06 2010 - 22:25:37 CEST