Parse XML to Oracle SQL

Question

I have the following XML message:

<?xml version="1.0" encoding="UTF-8"?>
<MSH>
   <MSH.1>|</MSH.1>
   <MSH.2>^~\&amp;</MSH.2>
   <MSH.3>
      <HD.1>LAB</HD.1>
   </MSH.3>
   <MSH.4>
      <HD.1>767543</HD.1>
   </MSH.4>
   <MSH.5>
      <HD.1>ADT</HD.1>
   </MSH.5>
   <MSH.6>
      <HD.1>767543</HD.1>
   </MSH.6>
   <MSH.7>199003141304-0500</MSH.7>
   <MSH.9>
      <CM_MSG.1>ACK</CM_MSG.1>
      <CM_MSG.3>ACK_ACK</CM_MSG.3>
   </MSH.9>
   <MSH.10>XX3657</MSH.10>
   <MSH.11>
      <PT.1>P</PT.1>
   </MSH.11>
   <MSH.12>
      <VID.1>2.4</VID.1>
   </MSH.12>
</MSH>

I need to convert this into the following table:

Node Level 1      Node Level 2        Node Level 3         Value
MSH               MSH.1                                    |
MSH               MSH.2                                    ^~\&
MSH               MSH.3               HD.1                 LAB

I found a way to fill value in Oracle SQL using ExtractValue. But I didn't understand how to get the different nodes in XML and value dynamically.

How can I parse XML dynamically and store in the above table format depending on the number of node levels?

Answer 1

Full dynamic solution is not easy to implement.The main problem is generating dynamic amount of column in result set. To achieve this you have to utilize sophisticated technique :) example: Dyn pipeline
But if you can assume limit of level in your xml it will be much easier.

with xml_data as (select xmltype('<?xml version="1.0" encoding="UTF-8"?>
<MSH>
   <MSH.1>|</MSH.1>
   <MSH.2>lal</MSH.2>
   <MSH.3>
      <HD.1>LAB</HD.1>
   </MSH.3>
   <MSH.4>
      <HD.1>767543</HD.1>
   </MSH.4>
   <MSH.5>
      <HD.1>ADT</HD.1>
   </MSH.5>
   <MSH.6>
      <HD.1>767543</HD.1>
   </MSH.6>
   <MSH.7>199003141304-0500</MSH.7>
   <MSH.9>
      <CM_MSG.1>ACK</CM_MSG.1>
      <CM_MSG.3>ACK_ACK</CM_MSG.3>
   </MSH.9>
   <MSH.10>XX3657</MSH.10>
   <MSH.11>
      <PT.1>P</PT.1>
   </MSH.11>
   <MSH.12>
      <VID.1>2.4</VID.1>
   </MSH.12>
</MSH>') xd from dual)
select x.* from xml_data
,xmltable('//*[not(*)]' passing xd 
 columns  
    n_level_1    varchar2(4000) path '(ancestor-or-self::*/name(.))[1]'
   ,n_level_2   varchar2(4000) path '(ancestor-or-self::*/name(.))[2]'
   ,n_level_3   varchar2(4000) path '(ancestor-or-self::*/name(.))[3]'
   ,n_level_4   varchar2(4000) path '(ancestor-or-self::*/name(.))[4]'
   ,n_level_5   varchar2(4000) path '(ancestor-or-self::*/name(.))[5]'
   ,n_level_6   varchar2(4000) path '(ancestor-or-self::*/name(.))[6]'
   ,n_level_7   varchar2(4000) path '(ancestor-or-self::*/name(.))[7]'
   ,n_level_8   varchar2(4000) path '(ancestor-or-self::*/name(.))[8]'
   ,n_level_9   varchar2(4000) path '(ancestor-or-self::*/name(.))[9]'
   ,n_level_10  varchar2(4000) path '(ancestor-or-self::*/name(.))[10]'    
   --...n times
   ,n_value    varchar2(4000)  path './text()'  
 ) x;