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>

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>;
To: Anupam Bakshi <bakshia@yahoo.com>;
Cc: <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, Phone: +31 534893688, Fax: +31 534892927
Room: ZI 3039, WWW: http://www.cs.utwente.nl/~keulen