declare 
  gc_date      date := sysdate; 
  l_crsr sys_refcursor; 
 
  function to_xml1(a_cursor sys_refcursor) return xmltype is 
    l_xml  xmltype; 
  begin 
    execute immediate q'[alter session set nls_date_format = 'yyyy-mm-dd"T"hh24:mi:ss']'; 
    l_xml := xmltype.createxml(a_cursor); 
    close a_cursor; 
    execute immediate q'[alter session set nls_date_format = 'dd-MON-yy']'; 
    return l_xml; 
  end; 
 
  function to_xml2(a_cursor sys_refcursor) return xmltype is 
    l_xml  xmltype; 
    l_ctx number; 
  begin 
    execute immediate q'[alter session set nls_date_format = 'yyyy-mm-dd"T"hh24:mi:ss']'; 
    l_ctx := dbms_xmlgen.newContext(l_crsr); 
    l_xml := dbms_xmlgen.getxmltype(l_ctx); 
    dbms_xmlgen.closecontext(l_ctx); 
    close a_cursor; 
    execute immediate q'[alter session set nls_date_format = 'dd-MON-yy']'; 
    return l_xml; 
  end; 
 
  function to_xml3(a_cursor sys_refcursor) return xmltype is 
    l_xml  xmltype; 
  begin 
    execute immediate q'[alter session set nls_date_format = 'yyyy-mm-dd"T"hh24:mi:ss']'; 
    select xmlagg(value(a)) 
      into l_xml 
      from table(xmlsequence(a_cursor)) a; 
    close a_cursor; 
    execute immediate q'[alter session set nls_date_format = 'dd-MON-yy']'; 
    return l_xml; 
  end; 
 
begin 
    open l_crsr for 
      select  gc_date-1 some_date, sysdate another_date, cast(null as number) num 
        from dual 
       connect by level <= 2; 
    dbms_output.put_line(to_xml1(l_crsr).getclobval()); 
 
    open l_crsr for 
      select  gc_date-1 some_date, sysdate another_date, cast(null as number) num 
        from dual 
       connect by level <= 2; 
    dbms_output.put_line(to_xml2(l_crsr).getclobval()); 
 
    open l_crsr for 
      select  gc_date-1 some_date, sysdate another_date, cast(null as number) num 
        from dual 
       connect by level <= 2; 
    dbms_output.put_line(to_xml3(l_crsr).getclobval()); 
end;