Gene Wirchenko <(E-Mail Removed)> wrote in
news:(E-Mail Removed):
> On 12 May 2011 00:25:29 GMT, "David-W-Fenton"
><(E-Mail Removed)> wrote:
>
>>John W. Vinson <jvinson@STOP_SPAM.WysardOfInfo.com> wrote in
>>news:(E-Mail Removed):
>>
>>> On Wed, 11 May 2011 08:11:43 -0700, croy <(E-Mail Removed)>
>>> wrote:
>>>
>>>>It seems with MS Access that it is understood that -1
>>>>corresponds with "Yes", and 0 corresponds with "No".
>>>>
>>>>Is that generally true for the database design community as
>>>>a whole?
>>>
>>> No. Not even Microsoft is consistant; in SQL/Server a Boolean
>>> field is stored as a Bit, with +1 being TRUE and 0 being FALSE.
>>>
>>> I think it's safe now to assert that 0 is FALSE and nonzero is
>>> TRUE, but do read the documentation carefully!
>>
>>If you program on that assumption, your code will be very
>>cross-compatible with all databases, seems to me. True is really
>>nothing more than NOT FALSE.
>
> It is a dangerous assumption. NOT can be a bitwise operator
> on
> integers.
But it's not in VBA, which is what you'd be using in Access.
Of course, it's certainly true that you could be using it in SQL, as
well, but if you're not writing passthroughs, it will be executed by
Jet/ACE, so results will be reliable.
> In two's-complement arithmetic, NOT 1 equals -2, and both
> are considered true by the non-zero is true assumption.
>
> If this is a concern, use a boolean type. If you can not do
> that, then determine true and false using something like
> true=0=0
> false=not true
> and then use those variable where you need boolean values.
I don't think any of this is relevant to any circumstances in which
one would be using Access as one's development platform.
That WAS what we were talking about, no?
--
David W. Fenton
http://www.dfenton.com/
contact via website only
http://www.dfenton.com/DFA/
Similar Threads
