Talk:Codd's 12 rules
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The contents of this entry seems to be a copy of what can be found here:
http://www.databaseanswers.com/codds_rules.htm
Note that this is (at least marked as) Chris Date's version, an interpretation of Codd's rules. Chris Date is himself a "thinker" in this field, and while quite insightful, also prone to re-interpreting the past (particularly when it comes to NULL and other concepts which have evolved over time.) It would be helpful if this entry had original quotes, mis-thoughts and all, no?
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[edit] 13 rules
There are 13 rules. Shouldn't the article (albeit not the title) be updated to reflect this, if we're going to include a "rule zero"? Neilc 01:19, 11 Aug 2004 (UTC)
- Codd himself called them 12 rules, even though there are, in fact, 13 rules. McKay 12:10, 13 September 2006 (UTC)
[edit] Reasons & examples
This article would be a lot more valuable if examples were shown to illustrate why the rules are necessary. I'll give an example example:
- For Rule 3 (regarding null values) There have been several reports [1] of law-enforcement agencies designating the use of a value (e.g. "NOTAG", "NO PLATE") on parking tickets to indicate the absence of a license plate on the violator's vehicle. Later, an individual jokingly or inadverdently registers a custom license plate having one of these key values and is inundated with notices regarding unpaid parking tickets.
--Theodore Kloba 16:21, July 21, 2005 (UTC)
- I'm not opposed to having examples on the pages, but I don't think that we want to clutter up the rules more than they already are. Maybe having some sort of summary at the top, and examples at the bottom. If you'd like to organize such an effort feel free. I've a bunch of examples (in SQL Systems mostly), of why violations of any of these rules are very bad. McKay 16:14, 26 July 2005 (UTC)
The interconnectivity of Rules 4 and 9. Rule 9 is very difficult to achieve (Dataphor), but for many reasons is very desirable, but without Rule 4, how are applications to be able to adapt, if it can't ask the DBMS what each of the tables look like. Removing a column from a table, and if the application doesn't look at the structure to see if the columnn is still there, who knows what will happen? (Well, the application develper might be able to figure it out, if he knows what he's doing. McKay 03:44, 13 August 2005 (UTC)
[edit] The Actual 12 Rules
I think that this article should have two main sections. The first section would be the actual rules, as stated by Codd, verbatim, without interpretation. This is the closest I could find: http://www.cse.ohio-state.edu/~sgomori/570/coddsrules.html The second section would be an elaboration of the rules and "what they mean". The distinction of course is to allow Wikipedians to separate the actual rules from sections they can supply valuable input into. // Brick Thrower 08:21, 11 September 2006 (UTC)
How about:
Rule [Rule #]: [Rule Name]:
- [Codd's description]
- [What it means]
Just an idea McKay 21:02, 11 September 2006 (UTC)
[edit] 13 Rules Revisited
There seems to be no discussion of Neilc's 2004 comment pointing out that there are actually 13 rules in the article while the article's title is Codd's 12 Rules. I note that links to this article from others, e.g. the one defining a true relational database management system, also refer to 12 rules. This certainly led me to expect to see 12 rules when I clicked on the Codd's 12 Rules hotlink on that page. I was first startled and then annoyed when I encoun- tered 13 rules instead of 12.
After looking into this matter, I've concluded that what this article refers to as Rule 1 should really be called Rule 0, since that is how it is referred to by commentators such as Date and Hite. I suggest four modifications to the article: 1) The first sentence could be modified to read "Codd's 12 rules are a set of rules proposed by......"; 2) A sentence could be added to the effect that "While Codd's rules are typically referred to as Codd's 12 Rules, references to them usually list 13 rules, starting with Rule Zero."; 3) the list of rules should be renumbered so as to run from Rule 0 through Rule 12; 4) a reference to Codd's 1985 Computerworld articles (Computerworld October 14th 1985 and Computerworld October 21st 1985) should be added somewhere in the first or second paragraph.
I'm writing this as a computer user, not a computing historian or information technologist, so I will leave it to others to evaluate my comments and make any suitable edits to the article rather than be presumptuous and actually edit it myself. --JRamlow 10:55, 13 September 2006 (UTC)
- The numbering of the rules seems correct, though such an introductary paragraph would be welcome. As would a link or reference to his original work. McKay 12:12, 13 September 2006 (UTC)
[edit] Reference to SQL
The sentence "In fact, however, the rules are so strict that even systems whose only interface is the SQL language fail on some of the criteria" seems to be completely out of place here. SQL does not guarantee in any way that the system is relational. It might be a good idea to rephrase that as "In fact, some of today's most popular and sophisticated systems fail on some of the criteria". Rkrush 12:32, 22 October 2006 (UTC)
