Talk:Superkey: Difference between revisions

Content deleted Content added

Inline

Revision as of 18:08, 2 May 2011

Computing Stub‑class Low‑importance

	This article is within the scope of WikiProject Computing, a collaborative effort to improve the coverage of computers, computing, and information technology on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.ComputingWikipedia:WikiProject ComputingTemplate:WikiProject ComputingComputing
Stub	This article has been rated as Stub-class on Wikipedia's content assessment scale.
Low	This article has been rated as Low-importance on the project's importance scale.
	This article has been automatically rated by a bot or other tool as Stub-class because it uses a stub template. Please ensure the assessment is correct before removing the `\|auto=` parameter.

Databases (inactive)

This article is within the scope of WikiProject Databases, a project which is currently considered to be inactive.DatabasesWikipedia:WikiProject DatabasesTemplate:WikiProject DatabasesDatabases

Remark

For the example, what is the point of having BLUE and blue? I think this poses confusion without explanation. JWHPryor 19:26, 13 December 2006 (UTC)JWHPryor[reply]

wouldn't all columns together also be a superkey? By the definition given in this article? --Avl 15:49, 20 February 2007 (UTC)[reply]

Yes, as long as the table or view you consider does not contain duplicate rows. 151.46.130.95 18:00, 8 March 2007 (UTC)[reply]

Aha, so the provided example does not list ALL superkeys? I think perhaps this should be made explicit, as it is written now, one may be given the impression that only the sets of columns listed constitute superkeys, when in fact, there are many more superkeys. --Avl 18:15, 26 March 2007 (UTC)[reply]

I changed the example so as to remove the ambiguity. --Nabav 14:13, 16 April 2007 (UTC)[reply]

Where did this term even come from? As far as I know, PostgreSQL, MySQL, Oracle, and Microsoft all use "primary key" to mean the ... primary key of a table. Without attribution, it seems like someone just made this up. Mephistopheles (talk) 15:45, 21 October 2009 (UTC)[reply]

By "this term", you mean "superkey"? Well, I've learnt this in database course many many years ago and I'm pretty sure "nobody just made this up", well... except those guys who were "fathers" of modern database relational models who were about ... 40 years ago. Is "40 years" qualified for "just"? :)

"Superkey" is different, far different, from "primary key". A primary key is necessarily a superkey, but a superkey is not necessarily a primary key. You must have confused superkey with candidate key. A primary key is the candidate key that you want to assign to database table for practical reason. 石庭豐 (talk) 18:08, 2 May 2011 (UTC)[reply]

I must say that the language in this article could be improved a lot. Compared to the simple explanation in the about.com article (http://databases.about.com/cs/administration/g/superkey.htm) the first sentence is just unnecessarily complex.

@@ Line 15: / Line 15: @@
 Where did this term even come from? As far as I know, PostgreSQL, MySQL, Oracle, and Microsoft all use "primary key" to mean the ... primary key of a table. Without attribution, it seems like someone just made this up. [[User:Mephistopheles|Mephistopheles]] ([[User talk:Mephistopheles|talk]]) 15:45, 21 October 2009 (UTC)
+: By "this term", you mean "superkey"?  Well, I've learnt this in database course many many years ago and I'm pretty sure "nobody '''just made''' this up", well... except those guys who were "fathers" of modern database relational models who were about ... 40 years ago.  Is "40 years" qualified for "just"? :)
+: "Superkey" is different, far different, from "primary key".  A primary key is necessarily a superkey, but a superkey is not necessarily a primary key.  You must have confused superkey with candidate key.  A primary key is the candidate key that you want to assign to database table for practical reason. [[User:石庭豐|石庭豐]] ([[User talk:石庭豐|talk]]) 18:08, 2 May 2011 (UTC)
 I must say that the language in this article could be improved a lot. Compared to the simple explanation in the about.com article (http://databases.about.com/cs/administration/g/superkey.htm) the first sentence is just unnecessarily complex.