• To: "'K. Ari Krupnikov'" <ari@c...>,<xml-dev@l...>
• Subject: RE: Question for updating existing XML file
• From: "Michael Kay" <michael.h.kay@n...>
• Date: Thu, 29 Jul 2004 08:49:36 +0100
• In-reply-to: <86zn5jr8zf.fsf@f...>
• Thread-index: AcR0/HqPnF6rVI6fQXOfzoRrFjx6FgAQ3P1A

> This would seem to undermine your assertion that XML query languages
> prove that declarative languages work for (XML) hierarchical
> databases. Unless there is something in XQuery that makes navigating
> these secondary relationships as easy as following an XPath, it seems
> to me that XML query languages neither prove nor disprove that
> assertion.

The ability to use a function call within a path expression provides a
reasonably good way of handling secondary relationships. It enables you to
write things such as

customer/customer.orders(.)/order-lines/order-line.product(.)/@code

to follow relationships where the details of the relationship is hidden in
the function implementation.

Another proposal that has been made is to allow user-defined axes. I quite
like that idea, but there seem to be others who hate it.

Michael Kay

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