Alexandr Savinov wrote:
> Paul schrieb:
>
>> Alexandr Savinov wrote:
>>
>>> Assume that we have a set of 3 values S = {1, 3, 10}. We want to
>>> aggreage them and apply some function func: A = func(S). Do we have a
>>> problem? No. Now remove some item from the set so that we have S = {1,
>>> 3} and then apply again the aggregation function. Do we have a
>>> problem? No.
>>>
>>> Having null values is actually a way of removing data items from
>>> consideration. In this example we apply the aggregation function to the
>>> set {1, 3} which is equivalent to applying it to the set {1, 3, null}.
>>
Most of the time, in database context NULL denotes, as you point out,
the _absence_ of a value where you would expect one - still you are
freely using "NULL value" as a special kind of value.
ISTM this is inviting a lot of non-issues.
Did you consider viewing "NULL value" as a contradictio in terminis?
Received on Mon Jun 06 2005 - 17:11:11 CDT
