XQuery behaves ambiguously when extended

Question

HI Gentlemen,
I am confronted with a syntax problem again which I can not overcome. Given the following XML instance (only relevant part included:)
<?xml version="1.0" encoding="ISO-8859-15"?>
<ehd:ehd ehd_version="1.40" xmlns:ehd="urn:ehd/001" xmlns="urn:ehd/icd/001">
  <ehd:header>
    <ehd:id EX="f7c33598-5afb-4694-8aa9-be975dc6869b" RT="1.2.276.0.76.3.1.1"/>
    <ehd:document_type_cd V="ICD" DN="ICD-Stammdatei" S="1.2.276.0.76.5.100"/>
    <ehd:service_tmr V="2011-07-01..2011-12-31"/>
    <ehd:origination_dttm V="2011-05-02+02:00"/>
    <ehd:provider>
      <ehd:organization>
        <ehd:id EX="74" RT="1.2.276.0.76.5.233"/>
        <ehd:organization.nm V="KBV"/>
        <ehd:addr>
          <ehd:ADL V="Kassenärztliche Bundesvereinigung, Dezernat 3"/>
          <ehd:STR V="Herbert-Lewin-Platz"/>
          <ehd:HNR V="2"/>
          <ehd:ZIP V="10623"/>
          <ehd:CTY V="Berlin"/>
        </ehd:addr>
        <ehd:telecom V="tel:++49 30 4005 2121"/>
        <ehd:telecom V="mailto:[email protected]"/>
        <ehd:telecom V="http://www.KBV.de/ita/register_C.html"/>
      </ehd:organization>
    </ehd:provider>
    <ehd:interface>
      <ehd:id EX="SDICD" RT="1.2.276.0.76.5.109"/>
      <ehd:interface.nm V="ICD-10-GM Stammdatei"/>
      <ehd:version V="1.4"/>
      <ehd:description V="ICD-10-GM Stammdatei der KBV im XML-Format, Version 2011, COPYRIGHT-HINWEIS: Diese Datei wird den Softwarehäusern, die Arztpraxissoftware herstellen, sowie den Kassenärztlichen Vereinigungen vom Dezernat 6 der KBV ausschließlich zur Nutzung in der vertragsärztlichen Versorgung zur Verfügung gestellt. Für alle sonstigen Nutzungszwecke wende man sich über den Servicedesk der KBV (EMail: [email protected], Telefon: 030 / 4005-2121) an das Dezernat 3 der KBV." URL="http://www.kbv.de/ita/register_C.html"/>
    </ehd:interface>
  </ehd:header>
  <ehd:body>
    <icd_stammdaten>
      <kapitel_liste>
        <kapitel>
          <nummer V="14"/>
          <von_icd_code V="N00"/>
          <bis_icd_code V="N99"/>
          <bezeichnung V="Krankheiten des Urogenitalsystems"/>
          <gruppen_liste>
            <gruppe>
              <von_icd_code V="N00"/>
              <bis_icd_code V="N08"/>
              <bezeichnung V="Glomeruläre Krankheiten"/>
              <diagnosen_liste>
                <diagnose>
                  <icd_code V="N00.-"/>
                  <bezeichnung V="Akutes nephritisches Syndrom"/>
                  <abrechenbar V="n"/>
                  <krankheit_in_mitteleuropa_sehr_selten V="n"/>
                  <schlüsselnummer_mit_inhalt_belegt V="j"/>
                  <infektionsschutzgesetz_meldepflicht V="n"/>
                  <infektionsschutzgesetz_abrechnungsbesonderheit V="n"/>
                  <diagnosen_liste>
                    <diagnose>
                      <icd_code V="N00.0"/>
                      <bezeichnung V="Akutes nephritisches Syndrom mit minimaler glomerulärer Läsion"/>
                      <abrechenbar V="j"/>
                      <krankheit_in_mitteleuropa_sehr_selten V="n"/>
                      <schlüsselnummer_mit_inhalt_belegt V="j"/>
                      <infektionsschutzgesetz_meldepflicht V="n"/>
                      <infektionsschutzgesetz_abrechnungsbesonderheit V="n"/>
                      <diagnosethesaurus_liste>
                        <diagnosethesaurus V="Glomerulusläsion"/>
                        <diagnosethesaurus V="Akutes nephritisches Syndrom mit minimaler glomerulärer Läsion"/>
                      </diagnosethesaurus_liste>
                      <kodierrichtlinien_liste>
                        <akr_ref V="B1400"/>
                        <akr_ref V="B1400p"/>
                      </kodierrichtlinien_liste>
                    </diagnose>
                    <diagnose>
                      <icd_code V="N00.1"/>
...My task is to query several <diagnose> elements using <icd_code> as the key for them. The key is unique in the whole instance document. Note that I am stepping up one node from the key (<icd_code>) to its parent (<diagnose>).
Now I experience the follfowing:
(1) Basic XQuery statement--works fine
SQL> SELECT XMLSerialize(DOCUMENT
  2  XMLQuery(
  3    'xquery version "1.0"; (: :)
  4       declare namespace n1="urn:ehd/001"; (: :)
  5       declare namespace n2="urn:ehd/icd/001"; (: :)
  6       element h {
  7         /n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX
  8       , /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:diagnose/n2:icd_code[@V="&code"]/..}'
  9    PASSING xml_document
10    RETURNING CONTENT
11  )
12  AS CLOB INDENT SIZE = 2
13  ) as result
14  FROM z
15  where id = 11
16  /
Geben Sie einen Wert für code ein: N08.8
alt   8:    , /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:diagnose/n2:icd_code[@V="&code"]/..}'
neu   8:    , /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:diagnose/n2:icd_code[@V="N08.8"]/..}'
RESULT                                                                                                                 
<h EX="74">                                                                                                            
  <diagnose xmlns="urn:ehd/icd/001">                                                                                   
    <icd_code V="N08.8"/>                                                                                              
    <bezeichnung V="Glomeruläre Krankheiten bei sonstigen anderenorts klassifizi                                       
erten Krankheiten  (I33.0+)"/>                                                                                         
    <abrechenbar V="j"/>                                                                                               
    <notationskennzeichen V="*"/>                                                                                      
    <krankheit_in_mitteleuropa_sehr_selten V="n"/>                                                                     
    <schlüsselnummer_mit_inhalt_belegt V="j"/>                                                                         
    <infektionsschutzgesetz_meldepflicht V="n"/>                                                                       
    <infektionsschutzgesetz_abrechnungsbesonderheit V="n"/>                                                            
    <kodierrichtlinien_liste>                                                                                          
      <akr_ref V="A06f"/>                                                                                              
      <akr_ref V="B1400"/>                                                                                             
    </kodierrichtlinien_liste>                                                                                         
  </diagnose>                                                                                                          
</h>                                                                                                                   
1 Zeile wurde ausgewählt.(2) XQuery statement extended with some additional elements--it will not convert to VARCHAR2, either
SQL>
SQL> SELECT XMLSerialize(DOCUMENT
  2  XMLQuery(
  3    'xquery version "1.0"; (: :)
  4       declare namespace n1="urn:ehd/001"; (: :)
  5       declare namespace n2="urn:ehd/icd/001"; (: :)
  6       element h {/n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX },
  7       element kap {element nummer {/n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/n2:nummer/@V} },
  8       element diagnose {/n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:icd_code[@V="&code"]/..}'
  9    PASSING xml_document
10    RETURNING CONTENT
11  )
12  AS clob INDENT SIZE = 2
13  ) as result
14  FROM z
15  where id = 11
16  /
Geben Sie einen Wert für code ein: N08.8
alt   8:    element diagnose {/n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:icd_code[@V="&code"]/..}'
neu   8:    element diagnose {/n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel/descendant::n2:icd_code[@V="N08.8"]/..}'
ERROR:
ORA-19012: XML-Fragment kann nicht in erforderlichen Datentyp konvertiert werden
Es wurden keine Zeilen ausgewählt(3) The same, extended further, but using $p for shorthand
SQL> SELECT XMLSerialize(DOCUMENT
  2  XMLQuery(
  3    'xquery version "1.0"; (: :)
  4       declare namespace n1="urn:ehd/001"; (: :)
  5       declare namespace n2="urn:ehd/icd/001"; (: :)
  6       let $p :=  /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel
  7       element h {/n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX },
  8       element kapitel {
  9            element nummer {$p/n2:nummer/@V},
10            element von_icd_code {$p/n2:von_icd_code/@V},
11            element bis_icd_code {$p/n2:bis_icd_code/@V},
12            element bezeichnung {$p/n2:bezeichnung/@V}
13                   },
14       element gruppe {
15            element von_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:von_icd_code/@V},
16            element bis_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:bis_icd_code/@V},
17            element bezeichnung {$p/n2:kapitel/n2:gruppen_liste/n2:gruppe/n2:bezeichnung/@V}
18                   },
19       element diagnose {$p/descendant::n2:icd_code[@V="&code"]/..}'
20    PASSING xml_document
21    RETURNING CONTENT
22  )
23  AS CLOB INDENT SIZE = 2
24  ) as result
25  FROM z
26  where id = 11
27  /
Geben Sie einen Wert für code ein: N08.8
alt  19:    element diagnose {$p/descendant::n2:icd_code[@V="&code"]/..}'
neu  19:    element diagnose {$p/descendant::n2:icd_code[@V="N08.8"]/..}'
FROM z
FEHLER in Zeile 25:
ORA-19114: XPST0003 - Fehler beim Parsen des XQuery-Ausdrucks: 
LPX-00801: XQuery syntax error at 'element'
5      element h {/n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX },
-      ^ Could anyone tell me where I am wrong? By carefully studying DataDirect's XQUERY: A GUIDED TOUR I can not find a solution.
Thank you in advance, kind regards,
Miklos HERBOLY

Answer 1

It is a horror. The two files are completely identical except for the hint:
Vergleichen der Dateien p21-hint.sql und P21-ORI.SQL
***** p21-hint.sql
SELECT /*+ no_xml_query_rewrite */
XMLSerialize(CONTENT
XMLQuery(
***** P21-ORI.SQL
SELECT XMLSerialize(CONTENT
XMLQuery(
*****Now, the original version 2 with child predicate does the following:
SQL> @p21-ori
SQL> SELECT XMLSerialize(CONTENT
  2  XMLQuery(
  3    'xquery version "1.0"; (: :)
  4       declare namespace n1="urn:ehd/001"; (: :)
  5       declare namespace n2="urn:ehd/icd/001"; (: :)
  6       let $p := /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel
  7       return (
  8       element h {/n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX },
  9       element kapitel
10       {
11         element nummer {$p/n2:nummer/@V},
12         element von_icd_code {$p/n2:von_icd_code/@V},
13         element bis_icd_code {$p/n2:bis_icd_code/@V},
14         element bezeichnung {$p/n2:bezeichnung/@V},
15         element gruppe
16         {
17           element von_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:von_icd_code/@V},
18           element bis_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:bis_icd_code/@V},
19           element bezeichnung {$p/n2:gruppen_liste/n2:gruppe/n2:bezeichnung/@V},
20           element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="&code"]}
21         }
22       }
23  )'
24    PASSING xml_document
25    RETURNING CONTENT
26  )
27  AS clob INDENT SIZE = 2
28  ) as result
29  FROM z
30  where id = 11
31  /
Geben Sie einen Wert für code ein: N80.8
alt  20:        element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="&code"]}
neu  20:        element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="N80.8"]}
RESULT                                                                                                                 
<h EX="74"/>                                                                                                           
<kapitel>                                                                                                              
  <nummer/>                                                                                                            
  <von_icd_code/>                                                                                                      
  <bis_icd_code/>                                                                                                      
  <bezeichnung/>                                                                                                       
  <gruppe>                                                                                                             
    <von_icd_code/>                                                                                                    
    <bis_icd_code/>                                                                                                    
    <bezeichnung/>                                                                                                     
    <diagnose/>                                                                                                        
  </gruppe>                                                                                                            
</kapitel>                                                                                                             
1 Zeile wurde ausgewählt.
SQL> spool offAnd version 2 with the proposed hint behaves like this:
SQL> @p21-hint
SQL> SELECT /*+ no_xml_query_rewrite */
  2  XMLSerialize(CONTENT
  3  XMLQuery(
  4    'xquery version "1.0"; (: :)
  5       declare namespace n1="urn:ehd/001"; (: :)
  6       declare namespace n2="urn:ehd/icd/001"; (: :)
  7       let $p := /n1:ehd/n1:body/n2:icd_stammdaten/n2:kapitel_liste/n2:kapitel
  8       return (
  9       element h {/n1:ehd/n1:header/n1:provider/n1:organization/n1:id/@EX },
10       element kapitel
11       {
12         element nummer {$p/n2:nummer/@V},
13         element von_icd_code {$p/n2:von_icd_code/@V},
14         element bis_icd_code {$p/n2:bis_icd_code/@V},
15         element bezeichnung {$p/n2:bezeichnung/@V},
16         element gruppe
17         {
18           element von_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:von_icd_code/@V},
19           element bis_icd_code {$p/n2:gruppen_liste/n2:gruppe/n2:bis_icd_code/@V},
20           element bezeichnung {$p/n2:gruppen_liste/n2:gruppe/n2:bezeichnung/@V},
21           element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="&code"]}
22         }
23       }
24  )'
25    PASSING xml_document
26    RETURNING CONTENT
27  )
28  AS clob INDENT SIZE = 2
29  ) as result
30  FROM z
31  where id = 11
32  /
Geben Sie einen Wert für code ein: N80.8
alt  21:        element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="&code"]}
neu  21:        element diagnose {$p/descendant::n2:diagnose[n2:icd_code/@V="N80.8"]}
ERROR:
ORA-19121: Doppelte Attribut-Definition - 
Es wurden keine Zeilen ausgewählt
SQL> spool offI am completely confused.
My database version is 11.2.0.2.0
Thanks, kind regards,
Miklos