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Home -> Community -> Mailing Lists -> Oracle-L -> Re: No Nulls? (was: Warehouse design: snowflake vs star schem
RE: No Nulls? (was: Warehouse design: snowflake vs star schem>Or you'll have to explain to the HR manager why all of the employees appear to be terminated!
they aren't terminated! at least not yet :-)
Igor Neyman, OCP DBA
ineyman_at_perceptron.com
I disagree with the use of "dummy" values to represent missing data. It reminds me of the olden days when we coded in 12/31/99 and such. Shades of COBOL HIGH-VALUES! You're introducing a lot of dependencies and non-intuitive information. For instance, how do you ensure that these dummy values are used consistently across an application or database?
Yes, you will simply your SQL and perhaps improve performance (there are workarounds), but you will corresponding need to add special logic to reports and screens to suppress displaying these dummy values. Or you'll have to explain to the HR manager why all of the employees appear to be terminated!
A null value means there is missing data. It is not clear that 01/01/4000 represents missing data or incorrectly entered data.
Leave me my nulls!
Marc Perkowitz
END_EMPLOYEMENT date for still employed employees equals to "01/01/4000" (or any other pre-defined date in distant future).
Igor Neyman, OCP DBA
ineyman_at_perceptron.com
"No application that I can reasonably think of should
use NULLS, except those pre-81
where there are obsolete columns."
Everytime somebody says this to me, I ask them:
How do you handle still employed employees in an EMPLOYEE table
that contains a END_EMPLOYEMENT date column?
What's your take?
----
Matt Adams - GE Appliances - matt.adams_at_appl.ge.com
Write a poem about a haircut! But lofty, noble, tragic, full of love,
treachery, retribution, quiet heroism in the face of certain doom!
Six lines, cleverly rhymed, and every word beginning with the letter s!
-----Original Message-----
From: dgoulet_at_vicr.com [mailto:dgoulet_at_vicr.com]
Sent: Monday, October 14, 2002 2:29 PM
To: Multiple recipients of list ORACLE-L
Subject: Re:No Nulls? (was: Warehouse design: snowflake vs star schem
Jesse,
I'll refrain from personal comments, but on CJ's quote, he's correct. Nulls
are an oddity. They cannot be true or false (<column_name> = NULL or
<column_name> != NULL), nor can they equal anything. They are in effect a third
logical state of nothingness. You also have to code most applications with
indicator variables to check for their existence. All in all a real pain in the
backside. BUT, if you give me the possibility that nulls exist in the data I
much prefer using them vs. many a third party solution of a single space. No
application that I can reasonably think of should use NULLS, except those pre-81
where there are obsolete columns.
Dick Goulet
____________________Reply Separator____________________
Author: "Jesse; Rich" <Rich.Jesse_at_qtiworld.com>
Date: 10/14/2002 9:33 AM
On the link below is this quote from C.J.Date:
"I don't want you to think that my SQL solution to your problem means I
advocate the use of nulls. Nulls are a disaster."
Of course, he doesn't expound upon it (probably not a need except for
dummies like me). Anyone care to comment? (On the quote, not on my
dumminess...)
Rich
Rich Jesse System/Database Administrator
Rich.Jesse_at_qtiworld.com Quad/Tech International, Sussex, WI USA
> -----Original Message-----
> From: Robson, Peter [mailto:pgro_at_bgs.ac.uk]
> Sent: Monday, October 14, 2002 4:59 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Warehouse design: snowflake vs star schemas
>
>
> Just for the record (and perhaps to confirm that there are
> always two sides
> to a story). Readers may like to see the article Chris Date
> wrote to Ralph
> Kemball on the subject of business rules and integrity constraints:
>
> http://www.dbdebunk.com/kimball1.htm
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Author: Jesse, Rich
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-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Igor Neyman INET: ineyman_at_perceptron.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Mon Oct 14 2002 - 16:18:49 CDT
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