Concatenate elements with same name in sequence

Question

version 9.2
I have a clob column containing xml - unregistered
Some of the old xml has multiple <notes> elements and the new xml has one <notes> element. I have made a view that successfully extracts the xml from the column and it works great, but when I have multiple <notes> elements the view fails since I am using extractvalue(). I need to select the <notes> tags concatenated into one column in sequence when I have multiples. I am guessing the sequence should be as they appear in the xml document from top to bottom since there is no sequence attribute. I know how to use xmlsequence and xmltable to get the individual <notes> tags but they are not concatenated. Is there a magic xmlsequence/concatenation function that will do what I want here?
-- old xml
<Accident>
   <Case>
      <TRACS_Case_Number Value="7777777"/>
      <Notes>V-1 AND V-2 N/B TRANSIT RD (ST 78\) SLOWING TO MERGE INTO TRAFFIC.  V-3 N/B TRANSIT RD. </Notes>
      <Notes>STRIKES V-2 IN REAR AND PUSHES V-2 INTO V-1 STRIKING V-1 IN REAR WITH FRONT OF V-2 .  </Notes>
      <Notes>NO INJURIES.</Notes>
   </Case>
</Accident>-- new xml
<Accident>
   <Case>
      <TRACS_Case_Number Value="7777777"/>
      <Notes>V-1 AND V-2 N/B TRANSIT RD (ST 78) SLOWING TO MERGE INTO TRAFFIC.  V-3 N/B TRANSIT RD. STRIKES V-2 IN REAR AND PUSHES V-2 INTO V-1 STRIKING V-1 IN REAR WITH FRONT OF V-2 .  NO INJURIES.</Notes>
   </Case>
</Accident>I am also trying to register this xml to improve performance. However, when I see things like this in the xml I wonder what will happen when I try to register this xml. The DTD, I have no XSD, currently only supports one <notes> tag. Do I have to clean up all the xml in column to match the current DTD before registering? I could also use a good, EASY, example of how to register a schema.
Thanks...

Answer 1

You can use the string aggregation technique to concatenate the Notes element.
sql> WITH xmltable AS
  2    (SELECT xmltype('<Accident>
  3     <Case>
  4        <TRACS_Case_Number Value="7777777"/>
  5        <Notes>V-1 AND V-2 N/B TRANSIT RD (ST 78\) SLOWING TO MERGE INTO TRAFFIC.  V-3 N/B TRANSIT RD. </Notes>
  6        <Notes>STRIKES V-2 IN REAR AND PUSHES V-2 INTO V-1 STRIKING V-1 IN REAR WITH FRONT OF V-2 .  </Notes>
  7        <Notes>NO INJURIES.</Notes>
  8     </Case>
  9  </Accident>') xmlcol
10     FROM dual)
11  SELECT SUBSTR(replace(MAX(sys_connect_by_path(notes,   ':')),':',' '),   2) Notes
12  FROM
13    (SELECT extractvalue(t.column_value,    '/Notes/text()') notes,
14       rownum rn
15     FROM xmltable xt,
16       TABLE(xmlsequence(EXTRACT(xmlcol,    'Accident/Case/Notes'))) t)
17  CONNECT BY PRIOR rn = rn -1 START WITH rn = 1;
NOTES
V-1 AND V-2 N/B TRANSIT RD (ST 78\) SLOWING TO MERGE INTO TRAFFIC.  V-3 N/B TRANSIT RD.  STRIKES V-2 IN REAR AND PUSHES
G V-1 IN REAR WITH FRONT OF V-2 .       NO INJURIES.