InstantForum.NET v2.9.0SQLServerCentralhttp://www.sqlservercentral.com/Forums/notifications@sqlservercentral.comFri, 24 May 2013 03:27:54 GMT20http://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxGreat question. You got me at "unique value for every row".Tue, 25 Oct 2011 23:43:13 GMTKoen Verbeeckhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxThanks for the question Tom.Thu, 13 Oct 2011 07:54:08 GMTSQLRNNRhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxYou always submit tough questions. Thanks for making us think.Thu, 13 Oct 2011 05:45:37 GMTBritt Cluffhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxvery good question!!!thanks Tom!!Thu, 13 Oct 2011 05:23:17 GMTrfr.ferrarihttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxGood question tomThu, 13 Oct 2011 03:56:25 GMTDanny Oceanhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxThanks, now it's clear that my english has to be improved. :-DThu, 13 Oct 2011 03:48:58 GMTpalotaiarpadhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspx[quote][b]palotaiarpad (10/12/2011)[/b][hr]Hmmmm.I used the same source (http://en.wikipedia.org/wiki/Database_normalization) i hope (because the link provided on the result page isn't existing), and there is a definition: [u]A prime attribute, conversely, is an attribute that does occur in any candidate key.[/u]But is it wrong then?[/quote]Not the same page, but one just as good; I'm not sure what happened to that reference, it was cut and paste from my browser address bar. The definition on the wikipedia page you found contained a strange use of "any": "any" meaning "some". This is sort of logical but is a very unusual usage, so people get confused when "any" is used like that, and sometimes think it means "every". That wikipedia page has now been corrected and uses "some" instead of "any" which should be clearer. The writer of the original definition on the wikipedia page can be excused because he probably though that misinterpretation of that "any" would be avoided by that little word "conversely", which is saying that "prime" is the converse of "non-prime" which is defined immediately above (and the converse of "it isn't in any candidate key" is "it is in some candidate key") but it's better to avoid unusual usage and aim for clarity in something like wikipedia.Wed, 12 Oct 2011 11:42:10 GMTL' Eomot Inverséhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxThanks for the question Tom. Your questions always make my brain hurt.Wed, 12 Oct 2011 11:31:14 GMTTrey Stakerhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxOops, mistook the word "every" for "any" in the candidate key answers.Wed, 12 Oct 2011 11:26:53 GMTcharles evanshttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxNice question. Took much too long to shake the cobwebs out of my brain.Wed, 12 Oct 2011 09:34:33 GMTbitbucket-25253http://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxToo bad half right doesn't count for anything...Good question, Tom!Wed, 12 Oct 2011 09:11:18 GMTRob Schripsemahttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspx[quote][b]palotaiarpad (10/12/2011)[/b][hr]Hmmmm.I used the same source (http://en.wikipedia.org/wiki/Database_normalization) i hope (because the link provided on the result page isn't existing), and there is a definition: [u]A prime attribute, conversely, is an attribute that does occur in any candidate key.[/u]But is it wrong then?[/quote]The context here is that Non-Prime attribute does not occur in any candidate key, so CONVERSELY, a PRIME attribute does occur in any [but not all] candidate keysThe statement is correct, however the WIKI definition could certainly be worded a little better...Wed, 12 Oct 2011 08:58:50 GMTOzYbOi d(-_-)bhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxThanks Tom. (open up QotD and knew immediately who wrote it! :-P )After your question last week I did some revision so was a little better prepared to tackle this one today. Certainly making me flex the ol' brain in areas that are not as regularly flexed! :-)Wed, 12 Oct 2011 08:51:34 GMTOzYbOi d(-_-)bhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxHmmmm.I used the same source (http://en.wikipedia.org/wiki/Database_normalization) i hope (because the link provided on the result page isn't existing), and there is a definition: [u]A prime attribute, conversely, is an attribute that does occur in any candidate key.[/u]But is it wrong then?Wed, 12 Oct 2011 07:43:53 GMTpalotaiarpadhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxDarn! I don't know why, but I checked "has a different value on each row".Nice question, Tom.Wed, 12 Oct 2011 06:35:04 GMTspaghettidbahttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxIt is very good question. I was sure about the half part. Got to revise lots of things.Basics matter!!Best Regards,SudhirWed, 12 Oct 2011 06:27:26 GMTCoolCodeSharehttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxGreat question Tom, I can say that as I surprised myself by getting the right answer :-DWed, 12 Oct 2011 05:26:44 GMTDugyChttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxInteresting question, TomThanks, really got the grey matter working on this one.Wed, 12 Oct 2011 00:36:06 GMTStewart "Arturius" Campbellhttp://www.sqlservercentral.com/Forums/Topic1188858-2681-1.aspxComments posted to this topic are about the item [B]<A HREF="/questions/Database+Design/74785/">Prime Attributes</A>[/B]Tue, 11 Oct 2011 21:46:48 GMTL' Eomot Inversé