Home » SQL & PL/SQL » SQL & PL/SQL » number of columns
number of columns [message #414570] Wed, 22 July 2009 13:37 Go to next message
miroconnect@yahoo.com
Messages: 202
Registered: April 2006
Senior Member
I need suggestions on best practices for no of columns in any table , Is it nice to have more than 10 columns in a table or should I separate them in to two or more table ? please suggest me whats the best practice for no of columns in any table ?
Re: number of columns [message #414571 is a reply to message #414570] Wed, 22 July 2009 13:42 Go to previous messageGo to next message
BlackSwan
Messages: 25033
Registered: January 2009
Location: SoCal
Senior Member
Design tables to Third Normal Form; regardless of the resultant number of columns.

http://en.wikipedia.org/wiki/Third_normal_form
Re: number of columns [message #414573 is a reply to message #414570] Wed, 22 July 2009 13:49 Go to previous messageGo to next message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Also Normalization.

Regards
Michel
Re: number of columns [message #414574 is a reply to message #414571] Wed, 22 July 2009 13:51 Go to previous messageGo to next message
miroconnect@yahoo.com
Messages: 202
Registered: April 2006
Senior Member
I tried reading that Its really hard for me please can you explain me in other form ?
Re: number of columns [message #414575 is a reply to message #414570] Wed, 22 July 2009 14:15 Go to previous messageGo to next message
BlackSwan
Messages: 25033
Registered: January 2009
Location: SoCal
Senior Member
If you do not understand words written there, why should we expect you to understand them written here?
It is not worth our time to re-write here what already exists.
Re: number of columns [message #414576 is a reply to message #414575] Wed, 22 July 2009 14:33 Go to previous messageGo to next message
miroconnect@yahoo.com
Messages: 202
Registered: April 2006
Senior Member
I meant something like this example

http://databases.about.com/od/administration/l/bldef_3nf.htm
Re: number of columns [message #414579 is a reply to message #414570] Wed, 22 July 2009 15:08 Go to previous messageGo to next message
BlackSwan
Messages: 25033
Registered: January 2009
Location: SoCal
Senior Member
Is your problem solved now?
Re: number of columns [message #414580 is a reply to message #414579] Wed, 22 July 2009 15:21 Go to previous messageGo to next message
miroconnect@yahoo.com
Messages: 202
Registered: April 2006
Senior Member
not yet I have to read normalization in much depth and just that little explanation does not answer my question , but sure it is a good start.
Re: number of columns [message #414581 is a reply to message #414576] Wed, 22 July 2009 15:22 Go to previous messageGo to next message
joy_division
Messages: 4640
Registered: February 2005
Location: East Coast USA
Senior Member
I have to admit, I think the Wikipedia explanation is too difficult to understand for the lay person. I had a tough time understanding it myself.
Re: number of columns [message #414606 is a reply to message #414581] Wed, 22 July 2009 22:27 Go to previous messageGo to next message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Is the OraFAQ Wiki example also too difficult (in your opinion)?

Regards
Michel

[Updated on: Wed, 22 July 2009 22:27]

Report message to a moderator

Re: number of columns [message #414791 is a reply to message #414606] Thu, 23 July 2009 08:18 Go to previous messageGo to next message
joy_division
Messages: 4640
Registered: February 2005
Location: East Coast USA
Senior Member
No, that one is very good. The other one looks like it was taken from a "theory" book (or written by lawyers). Reminds me of looking at a calculus book when you're in pre-school Wink
Re: number of columns [message #414805 is a reply to message #414791] Thu, 23 July 2009 09:38 Go to previous messageGo to next message
Michel Cadot
Messages: 64102
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
If someone has an idea to improve the example and shows what the 5thNF, it would be welcome, I didn't find any... I'm not sure I understand what 5NF can be...

Regards
Michel
Re: number of columns [message #414982 is a reply to message #414805] Fri, 24 July 2009 05:07 Go to previous message
ayush_anand
Messages: 417
Registered: November 2008
Senior Member
Fifth normal form deals with cases where information can be reconstructed from smaller pieces of information that can be maintained with less redundancy.
I find the information about 5NF quite useful in the below link
http://www.bkent.net/Doc/simple5.htm#label4.2

[Updated on: Fri, 24 July 2009 05:09]

Report message to a moderator

Previous Topic: Calling PL/SQL Procedure
Next Topic: selecting all data from a single row
Goto Forum:
  


Current Time: Fri Dec 02 14:14:51 CST 2016

Total time taken to generate the page: 0.08537 seconds