Updating an xmltype table

Question

hi,
I have two xmltype tables(eg. testTableSB and testTableNSB), first one is schema-based(conforms to schemaA) and the other one is non-schema-based.
So the default storage will be object-relational and CLOB respectively.
I load the same xml document in both the tables. Each table has one row only(suppose).
Later I use the update statement with updateXML() in RHS as following:
update testTableSB x
set value(x)=updatexml(value(x),'/Company/Person[2]/@Degree','PHD');
update testTableNSB x
set value(x)=updatexml(value(x),'/Company/Person[2]/@Degree','BA');
Both updates work. From the documentation, I came to know that in the first table it only updates the node or attribute value whereas in the second update, the whole document is repalced because it is CLOB based.
My confusion is in the second update since it seems updating (in this case) only the attribute value.
Please suggest.
One more question, how to check whether the storage option for the table is object-relational or CLOB. One option is to describe the table. In this way, it gives info for object-relational only not for CLOB. what is the other way to check it? Any data_dictionary table?
SQL> create table testTableNSB of XMLType;
Table created.
SQL> describe testTableNSB;
Name Null? Type
TABLE of XMLTYPE
Thanking in advance.

Answer 1

Hi
I as wrote I never tested this possibility... therefore I did the following test.
A table contains the following XML data:
SQL> select extract(value(o), '/optw/person')
2 from optw1_or_ot o
3 where existsnode(value(o), '/optw/person[@id=5]') = 1;
EXTRACT(VALUE(O),'/OPTW/PERSON')
<person id="5">
<lastname>String</lastname>
<firstname>String</firstname>
<sex>F</sex>
</person>
If I access the underlying structure, the query looks like this (notice that birthday is NULL):
SQL> select x.id, x.lastname, x.firstname, x.birthday, x.sex
2 from optw1_or_ot o, table(o.xmldata.persons) x
3 where x.id = 5;
ID LASTNAME FIRSTNAME BIRTHDAY SEX
5 String String F
If I update the data, it seams to work...
SQL> update table(select o.xmldata.persons
2 from optw1_or_ot o, table(o.xmldata.persons) x
3 where x.id = 5) t
4 set t.birthday = sysdate;
1 row updated.
SQL> select x.id, x.lastname, x.firstname, x.birthday, x.sex
2 from optw1_or_ot o, table(o.xmldata.persons) x
3 where x.id = 5;
ID LASTNAME FIRSTNAME BIRTHDAY SEX
5 String String 06-FEB-04 F
But if I select the XML data again, the data isn't available...
SQL> select extract(value(o), '/optw/person')
2 from optw1_or_ot o
3 where existsnode(value(o), '/optw/person[@id=5]') = 1;
EXTRACT(VALUE(O),'/OPTW/PERSON')
<person id="5">
<lastname>String</lastname>
<firstname>String</firstname>
<sex>F</sex>
</person>
It seams that Oracle also stores "control" information in another columns.
Therefore the only way to add such an element is through the updatexml() function.
Chris