Re: Antw: Re: Sobre las querys en XML

[rodrigo linuxave net]

> First some Citations:
> 'XQL is a notation for retrieving information from a document'
> and :
> 'The XQL Proposal, a superset of the XSL pattern syntax, addresses the
> information retrieval aspects of queries.'
> and:
> 'An important area commonly associated with query languages is
> database management functions including operations such as
> create, delete, update, insert. This area is not currently addressed
> by either XML-QL or by  XSL.'
>

ok, so for the moment, it's not database-oriented but document-oriented?

>
> Conclusion:
> XQL is some (powerfull) kind of (SQL-) select, that allows to extract data
> from within a arbitrary complex DOM-tree, but:
> - It doesn't support joins
> - AFAIK it doesn't support grouping
> - it has only one aggregate method count(), that AFAIK does something like
>      'SELECTCOUNT(*) FROM table WHERE condition'
>
> So I think XQL is no substitute for XmlQuery
>
> Of course there is a non-empty intersection of XQL and XmlQuery:
>
> If the XmlQuery happens to be a select, that extracts some data from
> a single table, it could by replaced by the correnponding XQL equivalent,
> because each table could be identified with a simple structured XML document.
>
> IMO this small intersection does justify a total redesign of XmlQuery.

well Gerhard, you and Vivien are the people who had put their work on the
XML queries, so I think a redesign of XmlQuery is ok only (and only if) there is
something useful to be added to what you've done. So, if you think XML queries are
more powerful than this XQL stuff, let's continue like this, and if in the future
we find that XQL are useful we can:
* add support to XML queries for XQL
* add XQL as an option "query language" to the report engine (that is, it will
support SQL, XML Queries and XQL)

or we could do what Derek says: create our own free standard (just dreaming?)

cheers