UpdateXML for non-existing attribute

Question

Hello
bellow are data for a sreange looking (for me) behaviour of updateXML.
Usually (i mean other languages) setting an xml node attribute causes attribute creation if it does not exist.
Here obviously that is not the case.
Q: Why and is it possible to create attribute during node update?
thank you
i
h3. general info
SQL> select * from v$version;
BANNER
Oracle9i Enterprise Edition Release 9.2.0.7.0 - Production
PL/SQL Release 9.2.0.7.0 - Production
CORE 9.2.0.7.0 Production
TNS for 32-bit Windows: Version 9.2.0.7.0 - Production
NLSRTL Version 9.2.0.7.0 - Production
SQL> select dbms_metadata.get_DDL('TABLE', 'X') FROM dual;
DBMS_METADATA.GET_DDL('TABLE',
CREATE TABLE "PCB_1209"."X"
( "NODE" "SYS"."XMLTYPE"
) PCTFREE 10
SQL>
SQL> insert into x values(Xmltype('<TOP><DATAID>111080</DATAID></TOP>'));
SQL> insert into x values(Xmltype('<TOP><DATAID lbl="test">111000</DATAID></TOP>'));
SQL> commit;
Commit complete
h3. correct part
SQL>
SQL> select extract(node, '/').getStringVal() as node
2 from x where extract(node, '//DATAID/text()').getNumberVal() = 111000;
NODE
<TOP>
<DATAID lbl="test">111000</DATAID>
</TOP>
SQL>
SQL> update x set node = updateXML(node,'//DATAID/@lbl','test_new')
2 where extract(node, '//DATAID/text()').getNumberVal() = 111000;
1 row updated
SQL> commit;
Commit complete
SQL>
SQL> select extract(node, '/').getStringVal() as node
2 from x where extract(node, '//DATAID/text()').getNumberVal() = 111000;
NODE
<TOP>
<DATAID lbl="test_new">111000</DATAID>
</TOP>
h3. wrong part
SQL>
SQL> select extract(node, '/').getStringVal() as node
2 from x where extract(node, '//DATAID/text()').getNumberVal() = 111080;
NODE
<TOP>
<DATAID>111080</DATAID>
</TOP>
SQL>
SQL> update x set node = updateXML(node,'//DATAID/@lbl','test_new')
2 where extract(node, '//DATAID/text()').getNumberVal() = 111080;
1 row updated
SQL> commit;
Commit complete
SQL>
SQL> select extract(node, '/').getStringVal() as node
2 from x where extract(node, '//DATAID/text()').getNumberVal() = 111080;
NODE
<TOP>
<DATAID>111080</DATAID>
</TOP>

Answer 1

Unusual, probably. Documented, yes. This is from 10.2 but would still be applicable to you and your situation.
http://download.oracle.com/docs/cd/B19306_01/server.102/b14214/chapter1.htm#FEATURENO05479
The current UpdateXML() function can only manipulate the content of existing nodes within an XML document. It cannot be used to add or remove nodes from a document. The only way to add or remove nodes from a document is to use the methods provided by the DOM API.So you are going to have to insert/create that attribute in the XML before you can update it. I was going to provide a link to some examples but I can't seem to recall where I saw them in the forums. I thought it was on {forum:id=75} but I can't find it now.