Use UPDATEXML function to update a portion of the doc : UPDATEXML « XML « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. XML
3. UPDATEXML

SQL>
SQL>
SQL> CREATE TABLE myTable
  2  (id  NUMBER PRIMARY KEY
  3  ,doc XMLType NOT NULL)
  4  XMLTYPE doc STORE AS CLOB
  5  /

Table created.

SQL>
SQL>
SQL> update myTable
  2  set doc = updateXml(doc, 'message/greeting/text()', 'test')
  3  where id = 1;

0 rows updated.

SQL>
SQL>
SQL> drop table myTable;

Table dropped.