Handling xml

Question

Hi,
I have the following tables & data ..
create table identity (IDENTITY_ID varchar2(100));
Insert into identity values ('100');
Insert into identity values ('101');
create table CM_ENCOUNTER (IDENTITY_ID varchar2(100), CSN varchar2(100));
Insert into CM_ENCOUNTER values ('100','3a1');
Insert into CM_ENCOUNTER values ('101','1a2');
create table CM_PATIENT (IDENTITY_ID varchar2(100), GENDER varchar2(100), race varchar2(100));
Insert into CM_PATIENT values ('100','F','AA');
Insert into CM_PATIENT values ('101','M','HA');
Insert into CM_PATIENT values ('101','F','EA');
create table CM_ENCOUNTER_RFV
(IDENTITY_ID varchar2(100), CSN_ID varchar2(100), LINE varchar2(100), ENC_REASON_NAME  varchar2(100));
Insert into  CM_ENCOUNTER_RFV values ('100','23vx','2', 'phone');
commmit;The output needed is :
<EvaluatePatient>
    <PatientInformation>
      <Patient>
          <mrn>100</mrn>
          <CSN>3a1</CSN>
          <Gender>F</Gender>
          <race>AA</race>
          <ID>23vx2</ID>
          <Name>phone</Name>
       </Patient>
     <Orders>   <!-- XML from orders here, if applicable --> </Orders>
     <Immunizations>    <!-- XML from orders here, if applicable --> </Immunizations>
     <ProblemList></ProblemList>
   </PatientInformation>
   <PatientInformation>
     <Patient>
       <mrn>101</mrn>
       <CSN>1a2</CSN>
       <Gender>M</Gender>
       <race>HA</race>
       <ID></ID>
       <Name></Name>
      </Patient>
     <Orders>   <!-- XML from orders here, if applicable --> </Orders>
     <Immunizations>    <!-- XML from orders here, if applicable --> </Immunizations>
     <ProblemList></ProblemList>
   </PatientInformation>
</EvaluatePatient>Based on the above, I created a table (which is of xml) ...not sure if it's good way or use the query as it is instead of creating a table.
Create table  temp_xml
as
  Select                     XMLELEMENT("PatientInformation",(XMLELEMENT("Patient",
                              XMLELEMENT("mrn", s.identity_id),
                              XMLELEMENT("CSN", m.csn),
                              XMLELEMENT("Gender", p.gender),
                              XMLELEMENT("race", p.race),
                              XMLELEMENT("ID", r.csn_id || r.line),
                              XMLELEMENT("Name", r.enc_reason_name))),
                              XMLELEMENT ("Orders", NULL),
                              XMLELEMENT ("Immunizations", NULL),
                              XMLELEMENT ("ProblemList", NULL)) cola
  from identity s
  join CM_ENCOUNTER m
  on m.identity_id = s.identity_id
  join CM_PATIENT   p
    on m.identity_id = p.identity_id
  left outer join CM_ENCOUNTER_RFV   r
    on m.identity_id = r.identity_id;Now, I need to write each record into xml file..
I have the following code..but right now, i have very few rows..SO, this works fine..
Just thinking about the future, where there will be millions of rows..possibly this code might lead to memory issues especially XMLAGG part...
Is there any other way instead of using XMLAGG or go with XMLAGG??
DECLARE
   -- Data Variables
   v_xml              XMLTYPE;
   v_blob             BLOB;
   v_data_length      NUMBER;
   -- Loop Control Variables
   v_offset           NUMBER             DEFAULT 1;
   v_chunk   CONSTANT NUMBER             DEFAULT 4000;
   -- UTL_FILE variables
   fh                 UTL_FILE.file_type;
BEGIN
   SELECT XMLELEMENT ("EvaluatePatient", XMLAGG (cola))
     INTO v_xml
     FROM temp_xml;
   -- Turn the XML into a BLOB to bypass any 4k and 32k issues
   v_blob := v_xml.getblobval (1);
   v_data_length := DBMS_LOB.getlength (v_blob);
   -- Open the file
   fh := UTL_FILE.fopen ('PLSQL_DIR', 'myxml.xml', 'wb', v_chunk);
   -- Da loop de loop
   LOOP
      -- Exit when our file offset is bigger than our file
      EXIT WHEN v_offset > v_data_length;
      -- Write the output chunk by chunk
      UTL_FILE.put_raw (fh, DBMS_LOB.SUBSTR (v_blob, v_chunk, v_offset),
                        TRUE);
      -- Increment the offset by the amount written
      v_offset := v_offset + v_chunk;
   END LOOP;
   -- Close the file and say byebye
   UTL_FILE.fclose (fh);
EXCEPTION
   WHEN NO_DATA_FOUND
   THEN
      -- We won't write any data, or even open the file,
      -- if the query return no rows
      NULL;
END;Also need to attach the soap envelope to the above xml output..
Not sure how add this ...
<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope"
xmlns:a="http://www.w3.org/2005/08/addressing"
xmlns:u="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<s:Header>
<a:Action s:mustUnderstand="1">urn:Epic-com:DecisionSupport.2012.Services.Patient.EvaluatePatient</a:Action>
<a:MessageID>Some unique string here</a:MessageID> -- generate unique string based on the file produced for audit purposes
<o:Security xmlns:o="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd">
     <u:Timestamp u:Id="_0">
         <u:Created>2012-11-06T21:36:36.244Z</u:Created>
         <u:Expires>2012-11-06T21:41:36.244Z</u:Expires>
     </u:Timestamp>
     <o:UsernameToken>
         <o:Username>username</o:Username>
         <o:Password Type="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-username-token-profile-1.0#PasswordText">password</o:Password>
     </o:UsernameToken>
</o:Security>
</s:Header>
<s:Body>
<EvaluatePatient xmlns="urn:Epic-com:DecisionSupport.2012.Services.Patient">
                  xml generated from above
</EvaluatePatient>
</s:Body>
</s:Envelope>Thanks.

Answer 1

user7431648 wrote:
Based on the above, I created a table (which is of xml) ...not sure if it's good way or use the query as it is instead of creating a table.Just query your base tables directly.
Were you intending to recreate the temp table every single time you want to extract data ?
I have the following code..but right now, i have very few rows..SO, this works fine..
Just thinking about the future, where there will be millions of rows..possibly this code might lead to memory issues especially XMLAGG part...
Is there any other way instead of using XMLAGG or go with XMLAGG??Do you want to extract all your data in a single file? No filter predicate ?
Are you also intending to send a SOAP message containing millions of logical records ?
The other way around XMLAgg is an iterative approach that will fetch each record and append them to a LOB.
SELECT XMLELEMENT ("EvaluatePatient", XMLAGG (cola))
INTO v_xml
FROM temp_xml;
-- Turn the XML into a BLOB to bypass any 4k and 32k issues
v_blob := v_xml.getblobval (1);
v_data_length := DBMS_LOB.getlength (v_blob);getBlobVal() is deprecated, use XMLSerialize instead :
SELECT XMLSerialize(document
         XMLElement( ... )
         as blob
         encoding ' ... '
Also need to attach the soap envelope to the above xml output..
Not sure how add this ...Well, the same way you build the body, using SQL/XML functions.