Oracle-L: RE: No Nulls? (was: Warehouse design: snowflake vs star schem

From: Jesse, Rich <Rich.Jesse_at_qtiworld.com>
Date: Mon, 14 Oct 2002 14:18:33 -0800
Message-ID: <F001.004E8982.20021014141833@fatcity.com>

Thinking about Matt's question, would it be "proper" to move the column to a EMP_TERMINATED table with an outer join on EMPNO? There wouldn’t be any NULLs...

Rich

Rich Jesse                           System/Database Administrator
Rich.Jesse_at_qtiworld.com              Quad/Tech International, Sussex, WI USA

-----Original Message-----

Sent: Monday, October 14, 2002 4:53 PM
To: Multiple recipients of list ORACLE-L

Both would likely do FTS since at any given time more than 50% of your employees will be current (have an end date of 1/1/4000' making it very unlikely that the cbo would choose this index. The RBO, would, but it would likely degrade not improve your performance.

John

Grabowy, Chris wrote:

Hmmm...but what about the index? Which is faster?

select * from table where END_EMPLOYMENT IS NULL;

select * from table where END_EMPLOYMENT = '01/01/4000';

I like NULL, but I am leaning towards Igor, and others, to agree upon and use a default value, or a "business sense" replacement value for NULL. I want to be able to take the awesome advantage of an index...versus FTS?

Am I headed in the wrong direction?? Any other thoughts??
-----Original Message-----

Sent: Monday, October 14, 2002 4:49 PM
To: Multiple recipients of list ORACLE-L

The problem I see with NO NULLS is that artificial data must be created, where the data is truly not known. Whether you deal with NULLs or artificial data, you will always have to code accordingly, so it is a wash. Igor's example is an good one. When I write an app to access the END_EMPLOYMENT date, I must handle a date of '01/01/4000'. Or I can handle the NULL condition. As a person who has had to support some very convoluted code, I'd rather deal with NULL. What if the employee record contained TERM_CODE? I would rather have the value NULL, meaning they have not been terminated rather than dealing with hard-coded or lookup values.
-----Original Message-----

Sent: Monday, October 14, 2002 2:14 PM
To: Multiple recipients of list ORACLE-L

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

Original Message ----- To: Multiple recipients of list ORACLE-L Sent: Monday, October 14, 2002 3:39 PM

"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-----

Sent: Monday, October 14, 2002 2:29 PM
To: Multiple recipients of list ORACLE-L

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, Susse

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Jesse, Rich
  INET: Rich.Jesse_at_qtiworld.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 - 17:18:33 CDT