Creating type error

Question

Hi all,
I have a problem/question: I want to create an object type that describes a XML node. As you all know, a XML node can consists of one or more subnodes. That's why I tought of this type:
create or replace
type xml_node
as object
    xml_tag     varchar2(50)
  , xml_value   varchar2(4000)
  , xml_subnode xml_node
  );but I can't compile it, oracle complains about it can't create a recursive type. Does someone know how to resolve this issue?
Thanks!
Tom

Answer 1

SQL> create or replace
  2  type xml_node
  3  as object
  4    (
  5      xml_tag     varchar2(50)
  6    , xml_value   varchar2(4000)
  7    , xml_subnode xml_node
  8    );
  9  /
Warning: Type created with compilation errors.
SQL> sho err
Errors for TYPE XML_NODE:
LINE/COL ERROR
0/0      PL/SQL: Compilation unit analysis terminated
1/1      PLS-00318: type "XML_NODE" is malformed because it is a non-REF
         mutually recursive type
SQL> create or replace
  2  type xml_node
  3  as object
  4    (
  5      xml_tag     varchar2(50)
  6    , xml_value   varchar2(4000)
  7     , xml_subnode REF xml_node
  8    );
  9  /
Type created.
SQL> This may not be the way you want to go but REF is the only mechanism for recursion (as the error message suggests). The documentation will tell you more about REFs.
Cheers, APC