Oracle XML Parsing - ORA-19202 and LPX-00601 - oracle

Question

I am new to XML parsing in oracle, I am getting ORA-19202: Error occurred in XML processing and LPX-00601: Invalid token for below query. Can anyone please help ?
TABLENAME = PARSEXML
COLUMN1('ID') = VARCHAR |COLUMN2('XML') = CLOB
<?xml version="1.0" encoding="UTF-8"?>
<ns4:TSTCLOB xmlns:ns4="http://example.org/test" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
<ns4:Rqst>
<ns2:Initiation>
<ns2:InitiationDetail>
<ns3:Channel>WEB</ns3:Channel>
<ns3:Unit>ABCD</ns3:Unit>
</ns2:InitiationDetail>
</ns2:Initiation>
</ns4:Rqst>
</ns4:TSTCLOB>
SELECT ID, EXTRACT(xmltype(XML), '\ns4:TSTCLOB\ns4:Rqst\ns2:Initiation\ns2:InitiationDetail\ns3:Unit') "unit"
FROM PARSEXML WHERE ID = '123'

Answer 1

1) Your example xml is not valid. It is using 4 namespace but only 2 are declared. You have to add this xmlns:ns2="Namespace2" xmlns:ns3="Namespace3"
<ns4:TSTCLOB xmlns:ns4="http://example.org/test" xmlns:ns2="Namespace2" xmlns:ns3="Namespace3" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
<ns4:Rqst>
<ns2:Initiation>
<ns2:InitiationDetail>
<ns3:Channel>WEB</ns3:Channel>
<ns3:Unit>ABCD</ns3:Unit>
</ns2:InitiationDetail>
</ns2:Initiation>
</ns4:Rqst>
</ns4:TSTCLOB>
2) In xpath you have to use slash instead of backslash \ -> / = '/ns4:TSTCLOB/ns4:Rqst/ns2:Initiation/ns2:InitiationDetail/ns3:Unit'
3) Extract method has 3 parameters, the last one is namespace string. If your xml is using other namespace except default one you have to specify this in extract method.
Extract(xml, '/ns4:TSTCLOB/ns4:Rqst/ns2:Initiation/ns2:InitiationDetail/ns3:Unit','xmlns:ns4="http://example.org/test" xmlns:ns2="Namespace2" xmlns:ns3="Namespace3" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"')
4*) Extract,ExtractValue are deprecated , you should use xmltable or xmlquery

Answer 2

Try this approach (simplified the XML for testing purpose):
with tmp as(
select
xmltype(to_clob('<?xml version="1.0" encoding="UTF-8"?>
<TSTCLOB>
<Rqst>
<Initiation>
<InitiationDetail>
<Channel>WEB</Channel>
<Unit>ABCD</Unit>
</InitiationDetail>
</Initiation>
</Rqst>
</TSTCLOB>')) tmp_xml
from dual)
select
xml_tbl.Channel,
xml_tbl.Unit
from
tmp,
xmltable(
'/TSTCLOB/Rqst/Initiation/InitiationDetail' passing tmp.tmp_xml
columns
Channel varchar2(6) path 'Channel',
Unit varchar2(6) path 'Unit') xml_tbl