How can I delete only one part of my xml file?

Question

Hello,
I stored more than 100 users in only one xmltype column. For instance
Create table agro(users XMLTYPE);
... and I inserted all users inside
INSERT INTO agro values(XMLTYPE
('<?xml version="1.0" encoding="ISO-8859-1"?>
<authentication><users><user>
<name>cocoon</name>
<password>cocoon</password>
<role>admin</role>
<title>Mr.</title>
<firstname>Walter</firstname>
<lastname>Cocoon</lastname>
<company />
<street />
<zipcode />
<city />
<country>DE</country>
<phone />
<fax />
<email />
<bankid />
<bankname />
<accountid />
</user>
... another user, etc.
</users></authentication>'));
Now I tried to delete only one part of this file. For example all persons with the name"cocoon".
I used for this target the following statement:
DELETE FROM agro agro
WHERE agro.users.extract('authentication/users/user/text()').getStringVal()= 'cocoon';
When I execute this statement, Oracle DB delete all users and not only with the name "Cocoon".
How can I delete only one part of my xml file?
Kind Regards
M R

Answer 1

This the expected behavoir. You uploaded a document containing multiple users and then asked XML DB to delete any documnet that contained a user with the name in question. The problem here is that you are creating a mega document that contains an aggregation of user documents but then trying to work with individual user documents. This is a bad idea.
In general XML does not understand the concept of a collection of documents. It can only operate on one document at a time. Hence the tendancy to aggregate individual documents into a single larger document. Once you have an XML database, you can perform operations on collections of document, as easily as you can perform operations on individual documents, so the need to aggregate the individual documents together disappears.
If you store each user document as a seperate document then your delete will work as expected.