New subject: Problems with XQuery matching records by compound key

23 Dec 2010


      Hi
I am trying to match records from two different documents. Match key
consists of two parts, so I simply build up a string from first and second
match key and separate it by a hypen
Here are source documents
*Events.xml*
<EVENTS>**
*    *<MSG id=*"{e8e85fdd-04d8-43ea-8090-e72337c3a30d}"* location=*"Prague"*
event=*"Christmass"*/>**
*    *<MSG id=*"{7c94b2fc-b97c-4c09-b694-9993bfb2b93c}"* location=*
"Bratislava"* event=*"Easterns"*/>**
*    *<MSG id=*"{bdbb11da-2c92-425d-9bf5-87c1e96e1bd4}"* location=*"Berlin"*
event=*"Berlinale"*/>**
</EVENTS>**
* *
*Reports.xml*
<REPORTS>**
*    *<MSG id=*"{abcd}"* location=*"Prague"* event=*"Christmass"*/>**
*    *<MSG id=*"{efgh}"* location=*"Bratislava"* event=*"Easterns"*/>**
*    *<MSG id=*"{ijkl}"* location=*"Paris"* event=*"FassionFest"*/>**
*    *<MSG id=*"{mnqr}"* location=*"Moscow"* event=*"BalletFestival"*/>**
</REPORTS>
I am trying to find for each report all events, which are having the same
location and event attributes
So I build intermediate variables, containing pre-calculated keys
And finally I try to find related events
*match.xq*
(:* *Construct* *matching* *keys* **for** *events* *:)**
*let** **$event-msg-keys** *:=* *
*    *(*for** **$event** **in** */EVENTS/MSG**
*    **return** *
*    *<EVENT-MSG id="{$event/@id}" key="{concat($event/@location, '-',
$event/@event)}"/>**
*    *)**
* *
(:* *Construct* *matching* *keys* **for** *reports* *:)**
* *
*let** **$report-msg-keys** *:=* *
*    *(*for** **$report** **in** */REPORTS/MSG* *
*    **return** *
*    *<REPORT-MSG id="{$report/@id}" key="{concat($report/@location, '-',
$report/@event)}"/>**
*    *)**
* *
(:* *Find* *all* *events,* *related* **to** *each* *report:)**
*for** **$report-msg** **in** **$report-msg-keys***
*let** **$report-msg-id** *:=* **$report-msg*/@id**
*let** **$report-msg-key** *:=* **$report-msg*/@key**
* *
*let** **$related-events** *:=* *
*    *(*for** **$event-msg** **in** **$event-msg-keys***
*     **where** **$event-msg*/@key* *=* **$report-msg-key***
*    **return** **$event-msg*)**
* *
*return***
<REPORT-MSG id="{$report-msg-id}" key="{$report-msg-key}">**
*  *<RELATED-EVENTS>{$related-events}</RELATED-EVENTS></REPORT-MSG>
However, resulting dokument does not show any related events
<REPORT-MSG id=*"{abcd}"* key=*"Prague-Christmass"*>**
*  *<RELATED-EVENTS/>**
</REPORT-MSG>**
<REPORT-MSG id=*"{efgh}"* key=*"Bratislava-Easterns"*>**
*  *<RELATED-EVENTS/>**
</REPORT-MSG>**
<REPORT-MSG id=*"{ijkl}"* key=*"Paris-FassionFest"*>**
*  *<RELATED-EVENTS/>**
</REPORT-MSG>**
<REPORT-MSG id=*"{mnqr}"* key=*"Moscow-BalletFestival"*>**
*  *<RELATED-EVENTS/>**
</REPORT-MSG>
*Versions of BaseX*
All the time I worked with GUI
1. I started testing on BaseX 6.3.4
   2. I used a bit more complex data and query
   3. After failing I tried on 6.3.1
   4. There I was unable to open the collection with complains about Index
   out of bound Java error
   5. Then I dropped the database and created it again. Trying to run the
   XQuery I got the same error.
   6. returned back to 6.3.4
   7. rewrote it to shorted sample, shown above
I wonder, what I am doing wrong. Any advice?
With best regards
Jan Vlčinský