Recursive Self Reference

Question

Hi,
I am trying to do a recursive self reference. Is this the best way of doing it as I keep getting errors?
SQL> CREATE OR REPLACE TYPE type_objtyp AS OBJECT (
2 type_id NUMBER (10),
3 type_name VARCHAR2 (100),
4 sub_type REF type_objtyp
5 )
6 NOT FINAL
7 /
Type created.
SQL> CREATE OR REPLACE TYPE data_objtyp
2 /
Type created.
SQL> CREATE OR REPLACE TYPE data_list_objtyp AS TABLE OF data_objtyp
2 /
Warning: Type created with compilation errors.
SQL> CREATE OR REPLACE TYPE data_objtyp AS OBJECT (
2 data_id NUMBER (10),
3 type_ref REF type_objtyp,
4 creation_date DATE,
5 child_list_ref REF data_list_objtyp
6 )
7 NOT FINAL
8 /
Warning: Type created with compilation errors.
SQL>
SQL> COMMIT
2 /
Commit complete.
SQL> show errors
Errors for TYPE DATA_OBJTYP:
LINE/COL ERROR
0/0 PL/SQL: Compilation unit analysis terminated
5/25 PLS-00532: Target of REF must be a complete or incomplete object
type.

Answer 1

you can't have a REF to a table type, only to object types. so, instead use a table of REFs:
-- incomplete declaration
create or replace type data_objtyp;
-- declare table type
create or replace type data_objtyp_list is table of REF data_objtyp;
-- complete data object declaration
create or replace type data_objtyp is object (
data_id NUMBER (10),
type_ref REF type_objtyp,
creation_date DATE,
child_list data_objtyp_list
NOT FINAL;
hope that helps... g