W3C home > Mailing lists > Public > www-webdav-dasl@w3.org > January to March 2003

Issue null-ordering

From: Julian Reschke <julian.reschke@gmx.de>
Date: Thu, 9 Jan 2003 17:40:07 +0100
To: <www-webdav-dasl@w3.org>
Message-ID: <JIEGINCHMLABHJBIGKBCIEEBGCAA.julian.reschke@gmx.de>

A long time ago, Amelia Carlson wrote:

  In the WebDAV SEARCH spec (5.6, DAV:orderby), it says that nulls sort low,
to match SQL92.
  However, SQL92 and SQL99 both say "Whether a sort key value that is null
is
  considered greater or less than a non-null value is
implementation-defined,
  but all sort key values that are null shall either be considered greater
than
  all non-null values or be considered less than all non-null values."
  (words taken from SQL99, 14.1 &lt;declare cursor&gt; General Rule 2)c), in
  reference to null handling for the &lt;order by clause&gt;. )
  I would note that in 5.5.3 WebDAV SEARCH says nulls are less than all
  other values in a comparison, so the DAV:orderby matches that statement,
  it just gives an inaccurate reason.

Seems to me that if SQL databases are free to decide where to sort NULL
values (as long as they are consistent), we probably need to be just as
flexible in DASL (otherwise we can't directly map to a SQL query).

Feedback appreciated,


Julian


<http://greenbytes.de/tech/webdav/draft-reschke-webdav-search-latest.html#rf
c.issue.null-ordering>

--
<green/>bytes GmbH -- http://www.greenbytes.de -- tel:+492512807760
Received on Thursday, 9 January 2003 11:40:39 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Sunday, 22 March 2009 03:38:09 GMT