Where Clause and XDT:Untyped Issues

[Michael Kay]

What's more, I would expect 

let $ad := fn:collection("xmldb:exist://db/my")//ad

to return a set containing several ad elements. The only way 

contains($ad/head,'Baseball')

can return true is if exactly one of those ad elements has a child called
head - which seems intrinsically rather unlikely. If there's more than one
head element, it fails with a type error; if there are none, it return
false.

Incidentally, it's a common mistake to imagine that contains() is a test for
set membership, rather than a test for the presence of a substring. I
suspect that might be happening here. But who knows.

Michael Kay
http://www.saxonica.com/

> -----Original Message-----
> From: http://x-query.com/mailman/listinfo/talk 
> [mailto:http://x-query.com/mailman/listinfo/talk] On Behalf Of Torsten Grust
> Sent: 02 February 2008 12:48
> To: Torsten Grust
> Cc: http://x-query.com/mailman/listinfo/talk; Wei, Alice J.
> Subject: Re:  Where Clause and XDT:Untyped Issues
> 
> Woops, I should have looked more closely.  $doc is bound to 
> atomic values, not nodes.
> 
> The observation about $ad being invariant in the loop 
> applies, though.  This appears ``fishy'': either all bindings 
> of $doc pass or none at all (you seem to observe the former).
> 
>     --Torsten
> 
> On Feb 2, 2008, at 13:41, Torsten Grust wrote:
> 
> > Hi Alice,
> >
> > it might very well be that
> >
> >  where contains($ad/head,'Baseball')
> >
> > should be replaced by
> >
> >  where contains($doc/head,'Baseball')
> >
> > ($ad is invariant in the loop and thus makes for a 
> questionable filter 
> > criterion).  It is hard to tell, though: as Mike already said, you 
> > didn't post (a sketch of) your data.
> >
> > Cheers,
> >   --Torsten
> >
> >
> > On Feb 1, 2008, at 23:31, Wei, Alice J. wrote:
> >
> >> Hi,
> >>
> >>   I believe I have been passing this question through, but 
> I think my 
> >> main question about not been able to put in a where clause in my 
> >> XQuery after my second let statement has been declared. In 
> return, I 
> >> receive all retrieved results is the issue.
> >>
> >> The code below has been modified from one of the members’  
> >> inspirations.  Apparently, no matter what I do, it appears 
> that the 
> >> where clause in the $sorted_result has never been taken into the 
> >> output generation. When executed the script, it gives me back 
> >> everything, whether or not the word “baseball” was in the head.
> >> I have 197 distinct values in my list.
> >>
> >> let $ad := fn:collection("xmldb:exist://db/my")//ad
> >> let $sorted_result:=
> >> for $doc in distinct-values($ad)
> >> where contains($ad/head,'Baseball')
> >> order by $doc
> >> return $doc
> >> for $r at $count in $sorted_result
> >> let $nodes := $ad[. = $r]
> >> return
> >> <ad>
> >> <statistics>
> >> Showing Result: {$count} / {count($sorted_result)} </statistics> 
> >> {$nodes} </ad>
> >>
> >> What I want here is just something simple, I want to be 
> able to put 
> >> in some form of where clause so I can eliminate more of my current 
> >> result output. [...]
> >
> >
> > -- 
> >  | Prof. Dr. Torsten Grust                         http://x-query.com/mailman/listinfo/talk |
> >  |                                 http://www-db.in.tum.de/~grust/ |
> >  |     Database Systems - Technische Universität München (Germany) |
> >
> >
> >
> >
> > _______________________________________________
> > http://x-query.com/mailman/listinfo/talk
> > http://x-query.com/mailman/listinfo/talk
> 
> -- 
>    | Prof. Dr. Torsten Grust                         http://x-query.com/mailman/listinfo/talk |
>    |                                 http://www-db.in.tum.de/~grust/ |
>    |     Database Systems - Technische Universität München (Germany) |
> 
> 
> 
> 
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