How to extract the element name of an XML Document

Question

This is how my xml file looks like:
<?xml version="1.0" encoding="UTF-8" ?>
- <nsiData>
- <instance timestamp="2011-05-25 19:01:00">
<AECI>47.00</AECI>
<EEI>-553.00</EEI>
<EES>-91.00</EES>
<EKPC>-22.00</EKPC>
<LGEE>-140.00</LGEE>
<MHEB>-1376.00</MHEB>
<MISO>-4725.00</MISO>
<MOWR>55.00</MOWR>
<ONT>-872.00</ONT>
<OVEC>-144.00</OVEC>
<PJM>-1438.00</PJM>
<SPA>-55.00</SPA>
<SPC>20.00</SPC>
<SWPP>69.00</SWPP>
<TVA>-69.00</TVA>
<WAUE>-158.00</WAUE>
</instance>
- <instance timestamp="2011-05-25 19:02:00">
<AECI>47.00</AECI>
<EEI>-555.00</EEI>
<EES>-91.00</EES>
<EKPC>-22.00</EKPC>
<LGEE>-148.00</LGEE>
<MHEB>-1375.00</MHEB>
<MISO>-4709.00</MISO>
<MOWR>55.00</MOWR>
<ONT>-871.00</ONT>
<OVEC>-144.00</OVEC>
<PJM>-1426.00</PJM>
<SPA>-55.00</SPA>
<SPC>20.00</SPC>
<SWPP>82.00</SWPP>
<TVA>-69.00</TVA>
<WAUE>-158.00</WAUE>
</instance>
</nsiData>
I want to extract the element name and the element value from this file. I was trying to do it this way:
SELECT datetime,
loc.aeci_value,
loc.eei_value
FROM temp_xmltype txml,
XMLTABLE ('/nsiData' PASSING xmldata) misolmp,
XMLTABLE ('/nsiData/instance' PASSING misolmp.object_value
COLUMNS
datetime VARCHAR2(100) PATH '/instance/@timestamp') misodt,
XMLTABLE ('/nsiData/instance' PASSING misolmp.object_value
COLUMNS
aeci_value VARCHAR2(100) PATH '/instance/AECI',
eei_value VARCHAR2(100) PATH '/instance/EEI') loc
WHERE txml.feed_id = 127
But doing it this way does not get me AECI as a column value. Is there any way to get the element name as a column value.
I am on 11gR2

Answer 1

The SQL statement you wrote returns 4 rows and there is only two AECI values in there. The corrected version of what you wrote should really be
SELECT loc.datetime,
       loc.aeci_value,
       loc.eei_value
  FROM temp_xmltype txml,
       XMLTABLE ('/nsiData/instance' PASSING txml.xmldata
                 COLUMNS
                 datetime   VARCHAR2(100) PATH '@timestamp',
                 aeci_value VARCHAR2(100) PATH 'AECI',
                 eei_value  VARCHAR2(100) PATH 'EEI') loc
WHERE txml.feed_id = 127;If you know the element name and want it returned as a column name, why not just hard code it in the SQL statement, such as
SELECT loc.datetime,
       'AECI' as AECI,
       loc.aeci_value,
       'EEI' AS EEI,
       loc.eei_value
  FROM temp_xmltype txml,
       XMLTABLE ('/nsiData/instance' PASSING txml.xmldata
                 COLUMNS
                 datetime   VARCHAR2(100) PATH '@timestamp',
                 aeci_value VARCHAR2(100) PATH 'AECI',
                 eei_value  VARCHAR2(100) PATH 'EEI') loc
WHERE txml.feed_id = 127;I suspect you are really looking for something like {message:id=9535532}
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