更新Oracle 12c中的非模式XMLType列？

Question

Is there any way to update a XMLType column in Oracle 12c if the xmltype object is not schema based - ie it is generated outside of the Oracle database? I am trying to update just one field within one XML record in the Oracle database. For a simple xml such as:

<a>
  <b>
    <c>
      <d1>foo</d1>
      <d2>bar</d2>
       ...
    </c>
  </b>
</a>

I would like to change the text in field d1 from foo to newText . Hence I have tried:

UPDATE myXmlTable
  SET myXmlColumn = updatexml(myXmlColumn ,
                              '/a/text()',
                              updatexml(extract(myXmlColumn , '/a/ *'),
                                        'b/c/d1/text()',
                                        'newText')
                              )

  WHERE rowid = 'AAAHUBAAoAAAA0SAAA';

However I obtain the error:

SQL Error: ORA-19030: Method invalid for non-schema based XML Documents.
ORA-06512: at "SYS.XMLTYPE", line 354
ORA-06512: at "DIC_OWNER.XML_TRIG", line 8
ORA-04088: error during execution of trigger 'DIC_OWNER.XML_TRIG'
19030. 00000 -  "Method invalid for non-schema based XML Documents."
*Cause:    The method can be invoked on only schema based xmltype objects.
*Action:   Don't invoke the method for non schema based xmltype objects.

How can I generalise my code to work for my non-schema xml file?

[Edit] Here is the trigger that is being used - I didn't create this

create or replace trigger xml_trig before insert
or update on myXmlTable
for each row

declare

  newxml XMLType;

begin

  newxml := :new.OBJECT_VALUE;
  XMLType.schemavalidate(newxml);

end;

Answer 1

Your trigger is validating the schema. Your sample XML doesn't have a schema. Assuming your real XML doesn't actually have a schema that you've omitted and that the update is removing, then it was presumably inserted into the table before the trigger was created.

You seem to have three choices:

1. update the XML to include a valid schema.

2. remove the trigger.

3. modify the trigger to skip the validation for non-schema XML:

create or replace trigger xml_trig
before insert or update on myXmlTable
for each row
begin
  if :new.myxmlcolumn.isschemabased() = 1 then
    XMLType.schemavalidate(:new.myxmlcolumn);
  end if;
end;
/

Or if you want to ensure all new entries are schema-based, only do that check on update:

  if inserting or :new.myxmlcolumn.isschemabased() = 1 then
    XMLType.schemavalidate(:new.myxmlcolumn);
  end if;

But that doesn't prevent an existing schema-based value being updated to a non-schema-based value.

Answer 2

Your update statement works but does not affect the xml. If you remove the superfluous second UPDATEXML it does what it is supposed to do.

CREATE TABLE myXmlTable (myXmlColumn XMLTYPE);

INSERT INTO myXmlTable (myXmlColumn) VALUES (XMLTYPE('<a>
                                                        <b>
                                                          <c>
                                                            <d1>foo</d1>
                                                            <d2>bar</d2>
                                                             ...
                                                          </c>
                                                        </b>
                                                      </a>'));

COMMIT; 

UPDATE myXmlTable
SET myXmlColumn = updatexml(myXmlColumn,
                          'a/b/c/d1/text()',
                                    'newText'),
COMMIT;

SELECT XMLSERIALIZE(DOCUMENT myXmlColumn INDENT)
FROM myXmlTable;

I have tested this with Oracle 11.2.

Answer 3

You can simplify your statement:

Sample data :

CREATE TABLE yourtable ( yourxmlcolumn ) AS
  SELECT XMLTYPE( '<a><b><c><d1>foo</d1><d2>bar</d2></c></b></a>' ) FROM DUAL;

Update :

UPDATE yourtable
SET yourxmlcolumn = UPDATEXML(
                      yourxmlcolumn,
                      '/a/b/c/d1/text()',
                      'newText'
                    );

Output :

UPDATEDXML
-------------------------------------------------
<a><b><c><d1>newText</d1><d2>bar</d2></c></b></a>