XML-QL

Lisa Rein lisarein at finetuning.com
Tue Sep 1 18:02:48 BST 1998


Jonathan:

We can sink our teeth into this elusive spec so we can compare them head
to head?  Is there a URL available?  I'm doing a query language round up
for xml.com

So far I've got:

SQL (of course)
XPointer
XML-QL
XQL?
Appel...

more?

thanks everybody,

lisa

Jonathan Robie wrote:
> 
> At 11:19 AM 9/1/98 +0100, Michael Kay wrote:
> 
> >My immediate reaction is to compare this not with SQL, but
> >with the new XSL "tree construction" facilities which
> >essentially provide an XML transformation language. I don't
> >have time to do a detailed point-by-point comparison but it
> >would certainly be a useful exercise. Conceptually they have
> >many similarities but there are many points of detail where
> >one is stronger than the other. I would think it is entirely
> >possible to devise a language that combines the power of
> >both without a significant loss of usability.
> 
> In fact, at Metastructures 98 I presented a language called XQL that uses a
> syntax very similar to XSL Patterns. This language was developed primarily
> by Joe Lapp of webMethods and me. Like XML-QL, XQL is declarative.
> 
> One of the significant differences between XML-QL and XQL is that XQL can
> do both hierarchy and sequence. The fundamental structural relationships in
> XQL are:
> 
> o       hierarchy
> 
>         o       parent/child
>         o       ancestor/descendant
> 
> o       sequence
> 
>         o       precedes
>         o       immediately precedes
> 
> o       position
> 
>         o       subscripts
>         o       ranges
> 
> I think sequence is pretty important in documents, though it is not
> important in many data-oriented systems. XML-QL's heritage in relational
> theory has caused it to ignore sequence.
> 
> Jonathan
> 
> jonathan at texcel.no
> Texcel Research
> http://www.texcel.no
> 
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