Re: NULLs: theoretical problems?
From: V.J. Kumar <vjkmail_at_gmail.com>
Date: Tue, 21 Aug 2007 01:13:31 +0200 (CEST)
Message-ID: <Xns9992C398369E5vdghher_at_194.177.96.26>
>> Jan Hidders <hidd..._at_gmail.com> wrote in
>> news:1187599195.269472.153110 _at_a39g2000hsc.googlegroups.com:
>>
>> > On 20 aug, 01:48, "V.J. Kumar" <vjkm..._at_gmail.com> wrote:
>> >> I wonder what the truth tables for 'AND' and 'OR' would look like
>> >> with the DEF operator. Could you show those tables ?
>>
>> > They would be the usual table you already gave:
>>
>> >> x y AND
>> >> -------
>> >> defined
>> >> 0 0 0
>> >> 1 0 0
>> >> 0 1 0
>> >> 1 1 1
>>
>> What is 'x AND y' equal to if x is '1' and y is not defined ?
Date: Tue, 21 Aug 2007 01:13:31 +0200 (CEST)
Message-ID: <Xns9992C398369E5vdghher_at_194.177.96.26>
Jan Hidders <hidders_at_gmail.com> wrote in news:1187645998.798282.58960_at_g4g2000hsf.googlegroups.com:
> On 20 aug, 17:14, "V.J. Kumar" <vjkm..._at_gmail.com> wrote:
>> Jan Hidders <hidd..._at_gmail.com> wrote in
>> news:1187599195.269472.153110 _at_a39g2000hsc.googlegroups.com:
>>
>> > On 20 aug, 01:48, "V.J. Kumar" <vjkm..._at_gmail.com> wrote:
>> >> I wonder what the truth tables for 'AND' and 'OR' would look like
>> >> with the DEF operator. Could you show those tables ?
>>
>> > They would be the usual table you already gave:
>>
>> >> x y AND
>> >> -------
>> >> defined
>> >> 0 0 0
>> >> 1 0 0
>> >> 0 1 0
>> >> 1 1 1
>>
>> What is 'x AND y' equal to if x is '1' and y is not defined ?
> > The database would not allow you to write that. If y is nullable then > it forces you to write "DEF y : x AND y".
What is DEF y : x AND y equal to if x is '1' and y is not defined ?
> > -- Jan Hidders > >Received on Tue Aug 21 2007 - 01:13:31 CEST