Error in creating nested table involving inheritence - oracle

Question

I have a somewhat complex structure as follows :
create or replace type user_typ as object(
user_id number(19,0),
username nvarchar2(40 char)
);
I inherit an applicant_typ from this :
create or replace type applicant_typ under user_typ (
resume_text nclob
);
My design involves jobs to which applicants can apply. To this end, I create an application_typ as follows :
create or replace TYPE Application_typ AS OBJECT (
application_id NUMBER,
candidate applicant_typ,
time_of_app DATE
);
CREATE TYPE Application_tab IS TABLE OF Application_typ;
And now I want to create an object type called Job_typ, and a table containing those objects, wherein there will be a nested table for applications :
CREATE OR REPLACE TYPE Job_typ AS OBJECT (
job_ID NUMBER,
company_ID NUMBER,
description NVARCHAR2(1000),
name NVARCHAR2(200),
application Application_tab,
MAP MEMBER FUNCTION job_no RETURN NUMBER,
MEMBER PROCEDURE no_of_applicants
);
All of this works fine. The issue is when I try to create a table of type Job_typ :
CREATE TABLE Job_tab OF Job_typ
NESTED TABLE application STORE AS application_nt;
This doesn't work, giving the error :
SQL Error: ORA-02320: failure in creating storage table for nested table column APPLICATION
ORA-22913: must specify table name for nested table column or attribute
02320. 00000 - "failure in creating storage table for nested table column %s"
*Cause: An error occurred while creating the storage table for the
specified nested table column.
What am I doing wrong?
EDIT : I tried some different things. If I change application_typ as follows :
CREATE OR REPLACE TYPE Application_typ AS OBJECT (
application_id NUMBER,
candidate User_Typ, -- NOTE: This attribute is now of type User_typ instead of the inherited type
time_of_app DATE,
);
CREATE TYPE Application_tab IS TABLE OF Application_typ;
Then everything else works, and I am able to create the Job table. Why do I get the error on using the inherited type?

Answer 1

I tried the following in Oracle 11.2.0.1 and didn't get any error. I made a slight change though:
CREATE OR REPLACE TYPE user_typ AS OBJECT
(
user_id NUMBER (19, 0),
username NVARCHAR2 (40 CHAR)
) NOT FINAL; -- << Notice the NOT FINAL keyword
create or replace type applicant_typ under user_typ (
resume_text nclob
);
CREATE OR REPLACE TYPE Application_typ AS OBJECT
(
application_id NUMBER,
candidate applicant_typ,
time_of_app DATE
);
CREATE TYPE Application_tab IS TABLE OF Application_typ;
CREATE OR REPLACE TYPE Job_typ AS OBJECT
(
job_ID NUMBER,
company_ID NUMBER,
description NVARCHAR2 (1000),
name NVARCHAR2 (200),
application Application_tab,
MAP MEMBER FUNCTION job_no
RETURN NUMBER,
MEMBER PROCEDURE no_of_applicants
);
CREATE TABLE Job_tab OF Job_typ
NESTED TABLE application
STORE AS application_nt;
While trying to create all your types and keywords, I got the error:
[Error] PLS-00590 (10.1): PLS-00590: attempting to create a subtype UNDER a FINAL type
This is because Oracle doesn't allow creation of a subtype on a FINAL type. If you don't define any finalizing clause for the base type, the default is FINAL.
Read more on Oracle Docs.
If you are coding for the real world (read industry), I'd advise against using nested tables as column types. You end up spending your entire life trying to nest and un-nest these. I'd suggest you normalize your schema as much as you can or need and leave nested tables for operations in PL/SQL code blocks.