David Portas wrote:
> "Neo" <neo55592_at_hotmail.com> wrote in message
> news:1187641160.234792.278400_at_i38g2000prf.googlegroups.com...
>
>>>>... NULLs ... There are better and more consistent ways
>>>>of describing missing values.
>>>
>>>Will you please elaborate on those methods you
>>>consider better and more consistent? Thank you.
>>
>>Dbd, a lightweight db that represents things by creating a network of
>>nodes (each equiv to an AND gate), has an alternative method of
>>dealing with NULLs. It is simply, don't create nodes to signify that
>>something is unknown because their absence already implies it.
>>
>>Suppose we store a person named john whose age is 30. Later, we want
>>to store a person named mary but her age is unknown. In RMDB, we can
>>1) Refuse to enter a tuple for mary.
>>2) Enter a tuple for mary but incurr a NULL for age.
>>3) Redesign schema, add table T_PersonAge, move data, update code/
>>queries, etc to avoid NULL.
>
> 4) Have the right schema to start with so that no problem arises.
But that would dampen the straw!
Received on Mon Aug 20 2007 - 17:57:56 CDT
