Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: First Impressions on Using Alphora's Dataphor

Re: First Impressions on Using Alphora's Dataphor

From: Jonathan Leffler <jleffler_at_earthlink.net>
Date: Fri, 27 Aug 2004 05:36:41 GMT
Message-ID: <JLzXc.14635$3O3.6681@newsread2.news.pas.earthlink.net>


Laconic2 wrote:
> What is the difference, if any, between UDTs and the domains
> generated by "CREATE DOMAIN" in some RDBMs and, I think, now
> included in the SQL standard?

The CREATE DOMAIN in standard SQL (well, SQL-92, but these things usually don't change much) is a pitiful, neutered non-entity, at least if C J Date is to be believed (and, from what little I know of CREATE DOMAIN, I believe him).

To a crude approximation, the difference is between a full type and a sort of shorthand for a built-in type plus possibly a check constraint which can be dropped even when columns that were defined using the domain name still exist in the database.

-- 
Jonathan Leffler                   #include <disclaimer.h>
Email: jleffler_at_earthlink.net, jleffler_at_us.ibm.com
Guardian of DBD::Informix v2003.04 -- http://dbi.perl.org/
Received on Fri Aug 27 2004 - 00:36:41 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US