How to convert ORACLE XML String - CLOB as Valid XML and fetch values using XPATH

  -- Create the test table with a CLOB column
  CREATE a table with name - "SampleXmlCLOB" along with following columns
  ID INTEGER PRIMARY KEY,
  Subject VARCHAR(256),
  XML_CLOB_STRING CLOB

Table created.

How to read value using XPATH :
SELECT XmlType(SampleXmlCLOB .XML_CLOB_STRING).EXTRACT('//DATAMATRIX/FSDATAMATRIX[1]/FIELD1/text()').GETSTRINGVAL() FROM 
SampleXmlCLOB  WHERE SampleXmlCLOB .ID = 100