Dbms_xmldom

Question

Hello there,
I'm new to XML and have been asked to produce an XML file from a table. I've viewed various sites and it appears the recommendation is to use "dbms_xmldom".
I have attached the DTD (my_dtd.txt) and an example of the required XML file (sample.xml).  I've also attached the PLSQL I'm using to extract the data and the result is below. I can't figure out how to prevent <impc_location_code> element from repeating or the place the elemnt <received_receptacle> in the output.
Any assistance is greatly appreciated.
Kind regards,
Paul
DECLARE
   l_xmltype XMLTYPE;
   l_domdoc dbms_xmldom.DOMDocument;
   l_root_node dbms_xmldom.DOMNode;
   l_rec_at_loc_element dbms_xmldom.DOMElement;
   l_rec_at_loc_node dbms_xmldom.DOMNode;
   l_rec_element dbms_xmldom.DOMElement;
   l_rec_node dbms_xmldom.DOMNode;
   l_loc_element dbms_xmldom.DOMElement;
   l_loc_node dbms_xmldom.DOMNode;
   l_loc_text dbms_xmldom.DOMText;
   l_loc_textnode dbms_xmldom.DOMNode;
   l_workstation_element dbms_xmldom.DOMElement;
   l_workstation_node dbms_xmldom.DOMNode;
   l_workstation_text dbms_xmldom.DOMText;
   l_workstation_textnode dbms_xmldom.DOMNode;
   l_amu_timestamp_element dbms_xmldom.DOMElement;
   l_amu_timestamp_node dbms_xmldom.DOMNode;
   l_amu_timestamp_text dbms_xmldom.DOMText;
   l_amu_timestamp_textnode dbms_xmldom.DOMNode;
BEGIN
   -- Create an empty XML document
   l_domdoc := dbms_xmldom.newDomDocument;
   -- Create a root node
   l_root_node := dbms_xmldom.makeNode(l_domdoc);
   -- Create a new node Rec_at_loc and add it to the root node
   l_rec_at_loc_element := dbms_xmldom.createElement(l_domdoc, 'received_receptacle_at_loc' );
   l_rec_at_loc_node := dbms_xmldom.appendChild(l_root_node,dbms_xmldom.makeNode(l_rec_at_loc_element));
   FOR r_rec IN (SELECT  impc_location_code
                       , receptacle_scan
                       , workstation
                       , to_char(amu_timestamp,'YYYY-MM-DD HH24:MI:SS') amu_timestamp
                    FROM my_table
   LOOP
      l_loc_element := dbms_xmldom.createElement(l_domdoc, 'impc_location_code ' );
      l_loc_node := dbms_xmldom.appendChild(l_rec_at_loc_node,dbms_xmldom.makeNode(l_loc_element));
      l_loc_text := dbms_xmldom.createTextNode(l_domdoc, r_rec.impc_location_code );
      l_loc_textnode := dbms_xmldom.appendChild(l_loc_node,dbms_xmldom.makeNode(l_loc_text));
      l_rec_element := dbms_xmldom.createElement(l_domdoc, 'receptacle_scan ' );
      dbms_xmldom.setAttribute(l_rec_element, 'cd', r_rec.receptacle_scan);
      l_rec_node := dbms_xmldom.appendChild(l_rec_at_loc_node,dbms_xmldom.makeNode(l_rec_element));
      l_workstation_element := dbms_xmldom.createElement(l_domdoc, 'workstation-id' );
      l_workstation_node := dbms_xmldom.appendChild(l_rec_node,dbms_xmldom.makeNode(l_workstation_element));
      l_workstation_text := dbms_xmldom.createTextNode(l_domdoc, r_rec.workstation );
      l_workstation_textnode := dbms_xmldom.appendChild(l_workstation_node,dbms_xmldom.makeNode(l_workstation_text));
      l_amu_timestamp_element := dbms_xmldom.createElement(l_domdoc, 'amu_timestamp' );
      l_amu_timestamp_node := dbms_xmldom.appendChild(l_rec_node,dbms_xmldom.makeNode(l_amu_timestamp_element));
      l_amu_timestamp_text := dbms_xmldom.createTextNode(l_domdoc, r_rec.amu_timestamp);
      l_amu_timestamp_textnode := dbms_xmldom.appendChild(l_amu_timestamp_node,dbms_xmldom.makeNode(l_amu_timestamp_text));
   END LOOP;
   l_xmltype := dbms_xmldom.getXmlType(l_domdoc);
   dbms_xmldom.freeDocument(l_domdoc);
   dbms_output.put_line(l_xmltype.getClobVal);
END;
MY RESULT
<received_receptacle_at_loc>
  <impc_location_code >SITE1</impc_location_code >
  <receptacle_scan  cd="123456789A">
    <workstation-id>976400194727994800</workstation-id>
    <amu_timestamp>2013-11-07 14:08:18</amu_timestamp>
  </receptacle_scan >
  <impc_location_code >SITE1</impc_location_code >
  <receptacle_scan  cd="123456789B">
    <workstation-id>976400194727994800</workstation-id>
    <amu_timestamp>2013-11-07 14:08:41</amu_timestamp>
  </receptacle_scan >
  <impc_location_code >SITE1</impc_location_code >
  <receptacle_scan  cd="123456789C">
    <workstation-id>976400194727994800</workstation-id>
    <amu_timestamp>2013-11-07 14:09:45</amu_timestamp>
  </receptacle_scan >
</received_receptacle_at_loc>

Answer 1

Hi Paul,
I've viewed various sites and it appears the recommendation is to use "dbms_xmldom".
Not really... or maybe it was, 15 years ago
The easiest way is to use SQL/XML functions :
select xmlserialize(document
         xmlelement("received_receptacle_at_loc"
         , xmlagg(
             xmlelement("received_receptacle"
             , xmlelement("impc_location_code", t.impc_location_code)
             , xmlagg(
                 xmlelement("receptacle_scan"
                 , xmlattributes(t.receptacle_scan as "cd")
                 , xmlelement("workstation-id", t.workstation)
                 , xmlelement("amu_timestamp", to_char(t.amu_timestamp,'YYYY-MM-DD HH24:MI:SS'))
                 order by t.receptacle_scan -- if needed
             order by t.impc_location_code -- if needed
         as clob
         indent -- for debugging purpose
from my_table t
group by t.impc_location_code ;
This will give you a CLOB on which you can further add the XML prolog and the DTD reference.