DevOps, CI/CD and Automation

Hi PL/SQL Gurus,

I have no experience in PL/SQL, but I have a requirement now where I have to use it.

We have a table with 10 columns, one of them is a CLOB and it holds XML data. The XMLs are very huge in size.
Two new columns are added to the table and the data has to be filled for the existing records from the corresponding XML. The XML has all the data as attributes. I started searching on the internet and tried if I could extract the data out of XML.

SELECT extractValue(value(x), '/Order/Package/@Code',
'xmlns:ns0="http://mycompany.com/Order/OrderType.xsd"' )

FROM ORDER_TABLE A
, TABLE(
XMLSequence(
extract(
xmltype(A.XML_DATA)
, '/ns0:Root'
, 'xmlns:ns0="http://mycompany.com/Order/OrderType.xsd"'
)
)
) x;

But this isn't working. Could anyone please provide some ideas.
I just want to confirm that I am able to extract data. Once this is done I would like to create a procedure so that all the existing records can be updated.

Thanks in advance.

Regards,
Fazzy