Writing XML data

Basic Oracle functions that allows you to manipulate xml data are:
- XMLAGG
- XMLCDATA
- XMLCOLATTVAL
- XMLCOMMENT
- XMLCONCAT
- XMLELEMENT
- XMLFOREST
- XMLPARSE
- XMLPI
- XMLQUERY
- XMLROOT
- XMLSEQUENCE
- XMLSERIALIZE
- XMLTABLE
- XMLTRANSFORM

Here is a simple example of an sql statement using xmlelement and xmlagg function:

select xmlelement
       ("People",
           (select xmlagg(xmlelement ("Person",
                          xmlelement("Id", p.id),
                          xmlelement("FirstName", p.firstname),
                          xmlelement("LastName", p.lastname))
                          )
            from person p)
       ).getClobVal()
 from dual

If you are using registered xsd schemas and types, you can just use the following function:

create or replace function from_people (p_people tro004_t) return clob is 
 v_schema_name varchar2(10) := 'People.xsd';
 v_schema_elem varchar2(10) := 'People';
begin
   RETURN xmltype(xmldata => p_people, schema => v_schema_name, element => v_schema_elem).getClobVal;
end;
/