Re: WWW/Internet 2009: 2nd CFP until 21 September
Date: Thu, 13 Aug 2009 01:47:51 -0400
"paul c" <toledobythesea_at_oohay.ac> wrote in message news:RtKgm.38901$Db2.23520_at_edtnps83...
> Mr. Scott wrote:
>> "Bob Badour" <bbadour_at_pei.sympatico.ca> wrote in message
>>> paul c wrote: >>> >>>> Mr. Scott wrote: >>>> ... >>>> >>>>> I'm confused. What requirement are you referring to? Are you >>>>> referring to the requirement that nulls be eliminated or the fact that >>>>> an order isn't an order without a delivery destination? The >>>>> referential cycle was a consequence of trying to eliminate nulls. ... >>> What cycle? And why would anyone care about a referential cycle? It's >>> not like SQL hasn't had deferred checking for a decade or two. >>
>> I think it's misleading to say that Sql has deferred checking. Both
>> deferred constraints and subquery in check are optional features of the
>> Sql standard. Neither Sql Server or DB2 support either. Oracle does
>> support deferred constraint checking but not subqueries in check.
> I gather you are no longer talking about sql, but about products.
Some of the features of Sql are not required to be implemented by all vendors. The products I listed are the top three database products sold and account for over 83% of the database market. In addition, neither Sybase (3.5%) nor Teradata (3.3%) support deferred constraint checking or subqueries in check constraints. Nearly half of the database systems being sold don't support deferred constraint checking and almost none support subqueries in check constraints. It is misleading to say that Sql has a feature when less than half of the Sql systems sold actually support it. Received on Thu Aug 13 2009 - 07:47:51 CEST