Nested table and inner nested tables (CREATE TABLE)

Question

Hello everyone,
I have a problem creating a table with some multilevel user-defined types (and therefore nested tables).
First of all the objects:
type top_object is object (
    text_top varchar2(100),
    table_a a_object_tbl,
    table_b b_object_tbl
type a_object_tbl is table of a_object;
type a_object is object (
  text_a varchar2(100)
type b_object_tbl is table of b_object;
type b_object is object (
  text_b varchar2(100),
  table_c c_object_tbl,
  table_d d_object_tbl
type c_object_tbl is table of c_object;
type c_object is object (
  text_c varchar2(100)
type d_object_tbl is table of d_object;
type d_object is object (
  text_d varchar2(100)
);Shortly: The TOP object contains tables of A and B. B contains tables of C and D.
Okay, now I want to create a table which is containing the TOP object.
My attempt:
create table multilevel_table (
  some_value varchar2(100),
  data top_object
NESTED TABLE top_object.table_a STORE AS data1,
NESTED TABLE top_object.table_b STORE AS data2
(NESTED TABLE table_c STORE AS data3,
NESTED TABLE table_c STORE AS data4);Obviously this does not work (otherwise I would not have been asking you ;) ). If I skip the "second level", so just by removing table_b from top_object and therefore the "inner nested table" it works.
But on this more complex scenario I don't know the right way or the syntax.
I would appreciate if I get any help or suggestions from you!

Answer 1

+1 for Hoek's recommendation of just not using NESTED TABLEs for persistent structures.
But:
create table multilevel_table (
  some_value varchar2(100),
  data top_object
NESTED TABLE data.table_a STORE AS data1,
NESTED TABLE data.table_b STORE AS data2
(NESTED TABLE table_c STORE AS data3,
NESTED TABLE table_d STORE AS data4) ;