RE: XML and Queries (not XQL)

[Michael Rys <mrys@microsoft.com>]

Title: RE: XML and Queries (not XQL)

I would like to disagree with Jonathan here. There are approaches to use (annotated) schemata (not necessarily DTDs) to define XML views over relational datat that then can be queried using an XML query language. XPath against annotated schemata in SQLServer 2000 is one example.

 

Also, please note that the use case R1 is representing only one potential serialization/view of relational data (and not my preferred one, I may add).

 

However, using the schema language alone to perform queries becomes pretty unwieldy. One of the best ways that utilize DataGuides (instance-inferred schema) for a visual query interface see Lore (the queries were translated into Lorel, Lore's query language).

 

Best regards

Michael

 

-----Original Message-----
From: Jonathan.Robie@SoftwareAG-USA.com [mailto:Jonathan.Robie@SoftwareAG-USA.com]
Sent: Thursday, February 22, 2001 9:32 AM
To: sellberg@kapow.dk; xml-dev@lists.xml.org
Subject: RE: XML and Queries (not XQL)

Selberg wrote:

> Are there examples of using XML as a substitute for
> an SQL query? I mean examples of using a DTD to define
> a valid search given as XML as the search criteria in
> a database?

I have seen several approaches to this. None of them seemed all that useful.

> Is it a good idea to make an abstraction of a
> valid database entity in a DTD and make an abstraction of
> a valid search criteria in a DTD? I have searched for such
> examples and I couldn't find any. Maybe the lack of such
> examples is telling me that it is not a way to go. XQL
> is not what we need.

The XML Query Working Group's use cases include "Use Case R" [1], which performs queries on an XML view of a relational database. The use case assumes these views are created automatically.

Jonathan

[1] Use Case R (http://www.w3.org/TR/xmlquery-use-cases#rdb)