Re: Do we really need NULL??

From: Saad Ahmad <sahmad_at_mfa.com>
Date: 12 Nov 1994 21:09:38 GMT
Message-ID: <3a3aui$phr_at_homer.alpha.net>

Sean Batten (k920699_at_kingston.ac.uk) wrote:
> What are the advantages and disadvantages of using NULL?

NULL means missing value. Depending on the application it might be necessary to use it, eg.
- The operator has to enter the dimensions of an object. There are

   some objects for which dimensions are not available. To represent    the data correctly he has to:

   .   Store -1 (or something like that)
   .   Have another field for (Is there data?)
   .   Store NULL [I think the neatest way]

- You have a system for measuring something. For different items

   that are measurable, there is a tolerance value (+- x), but for    some items you cannot use the system. You have the following options    . tolerance field has the tolerance or -1 for items for which

      the system cannot be used.
   . Have a separate field for Can system be used?    . Use NULL.

and so on ...`

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Received on Sat Nov 12 1994 - 22:09:38 CET