Re: Examples of SQL anomalies?
Date: Wed, 02 Jul 2008 10:05:39 -0300
David Cressey wrote:
> "Gene Wirchenko" <genew_at_ocis.net> wrote in message
>>-CELKO- <jcelko212_at_earthlink.net> wrote: >> >> >>>>>I do not use nulls in my tables. I still get null when I sum what
> turns out to be zero rows. If I want the total amount charged on invoices
> for a client in a certain date range, and there are no such invoices, the
> total is zero. <<
>>>No, that is flat wrong. There is no such invoice, so the question of >>>its total makes no sense. It is a totally different kind of thing >> >>>from an invoice that actually totaled to zero. Zero, empty set, empty >> >>>strings, NULLs, etc. are all different concepts around the idea of >>>missing data of some kind. >> >> If I want the total amount invoiced in a time period and there >>are no invoices, the total amount invoiced was zero. >> >> >>>Also, why are you using cursors? If you want to give this misleading >>>data, then use a COALESCE(invoice_tot, 0.00) in your code. >> >> Null is the misleading datum.
> Except that null isn't a datum. If you consider it a datum, that may be why
> you are misled.
Except that the total invoiced is a datum, and he requested that datum, which has no reason or excuse for NULL. Received on Wed Jul 02 2008 - 15:05:39 CEST