Forgot to send my response to the list:
-------- Original Message -------- Subject: Re: [basex-talk] Nothing gets printed after insert node Date: Wed, 06 Jun 2012 09:37:25 +0200 From: M. van Keulen m.vankeulen@utwente.nl Organization: University of Twente To: Anupam Bakshi bakshia@yahoo.com
Dear Anupam,
You seem to misunderstand the term "update". An update modifies the document in the database. So if you ask for it after that (with doc(...)) you'll get the modified document. In your case:
let $s := db:open("BaseX","sample1.xml") let $r := db:open("BaseX","result1.xml") for $m in $s//*:M return insert nodes $r//*:R[@id=$m/@id] into $m
modifies the sample1.xml in the database. A subsequent query db:open("BaseX","sample1.xml") would produce
<P> <M id="1"> <R id="1"/> </M> <M id="2"> <R id="2"/> </M> <M id="3"/> </P>
If you don't want to store the document in the database and modify it, but simply want to generate a *new* intermediary document that is similar to sample1.xml but which includes the desired R-elements, then you don't update anything (the original file stays the same). You can do this with
<P>{ let $s := db:open("BaseX","sample1.xml") let $r := db:open("BaseX","result1.xml") for $m in $s//*:M let $o := $r//*:R[@id=$m/@id] return <M>{$m/@*,$m/*,$o}</M> }</P>
or by using the transform-expression
let $s := db:open("BaseX","sample1.xml") let $r := db:open("BaseX","result1.xml") return copy $new := $s modify ( for $m in $new//*:M return insert nodes $r//*:R[@id=$m/@id] into $m ) return $new
Maurice
On 06-06-12 08:12, Anupam Bakshi wrote:
Hello Maurice, Thanks for your response. How do I communicate the intermediate result (modified document) between the two queries? Do I store the intermediate file back in the database? I tried to store the result of an update in a variable but it said that not allowed - "Let expression: No updating expression allowed". So the question is how can I run the first query to update the document and the second query to retrieve the modified document?
If someone can point to an example, that will help too. Best regards, Anupam
*From:* M. van Keulen m.vankeulen@utwente.nl *To:* Anupam Bakshi bakshia@yahoo.com *Cc:* basex-talk@mailman.uni-konstanz.de *Sent:* Wednesday, June 6, 2012 1:38 AM *Subject:* Re: [basex-talk] Nothing gets printed after insert node
Dear Anupam,
One workaround would be to do it in two queries: one to update your document, and one to retrieve the modified nodes.
The problem is not that you can't pick nodes from another resource, but that XQuery doesn't allow you to update and query inside the same query. In other words, within one query doing an update means you can't produce a (query) result, and having a query result means you can't do any update.
Regards, Maurice.
On 06-06-12 05:53, Anupam Bakshi wrote:
Then how about option 'b' ? At this point any way forward, any work around will do. Please let me know if anyone has any suggestion.
What I don't understand is, if I can add nodes why can't I pick those nodes from another resource? Why is this not possible?
But I'm looking for some workaround.
Thanks for your help. Anupam
*From: * Christian Grün christian.gruen@gmail.com mailto:christian.gruen@gmail.com; *To: * Anupam Bakshi bakshia@yahoo.com mailto:bakshia@yahoo.com; *Cc: * basex-talk@mailman.uni-konstanz.de mailto:basex-talk@mailman.uni-konstanz.de; *Subject: * Re: [basex-talk] Nothing gets printed after insert node *Sent: * Wed, Jun 6, 2012 12:24:18 AM
I'm interested in 'a'. The two files are in basex, I need to write a query that will
return the
modified nodes at run time.
Due to the nature of the XQuery Update Specification, that's generally not possible. Sorry for that.
From: Christian Grün christian.gruen@gmail.com; To: Anupam Bakshi bakshia@yahoo.com; Cc: basex-talk@mailman.uni-konstanz.de basex-talk@mailman.uni-konstanz.de; Subject: Re: [basex-talk] Nothing gets printed after insert node Sent: Tue, Jun 5, 2012 9:09:06 PM
Are you mostly interested in
a) updating your data, and returning the modified node(s) as query
result,
or b) finding the correct updating query to modify your data? ___________________________
Here is what I actually want to do. Maybe someone can suggest a straightforward way.
File : sample1.xml
<P> <M id="1"/> <M id="2"/> <M id="3"/> </P>
File: result1.xml
<Q> <R id="1"/> <R id="2"/> </Q>
Desired output :
<P> <M id="1"> <R id="1"/> </M> <M id="2"> <R id="2"/> </M> <M id="3"/> </P>
So insert the node from 2nd file into 1st where the ids match.
Thanks, Amupam
From: Christian Grün christian.gruen@gmail.com To: Anupam Bakshi bakshia@yahoo.com Cc: basex-talk@mailman.uni-konstanz.de Sent: Tuesday, June 5, 2012 12:02 PM Subject: Re: [basex-talk] Nothing gets printed after insert node
Unfortunately I did not see how I can return the value into a
variable
for further processing. Is there some other way to do it?
Did you already try db:output()?
--
Dr.Ir. M. van Keulen - Associate Professor, Data Management Technology Univ. of Twente, Dept of EEMCS, POBox 217, 7500 AE Enschede, Netherlands Email:m.vankeulen@utwente.nl mailto:m.vankeulen@utwente.nl, Phone: +31 534893688, Fax: +31 534892927 Room: ZI 3039, WWW:http://www.cs.utwente.nl/~keulen
basex-talk@mailman.uni-konstanz.de
-
M. van Keulen