CAST MULTISET using a recursive UDT using REF

Question

I am trying to create a recursive object and populate it using cast and multiset. However I keep getting the following error:
ORA-00932: inconsistent datatypes: expected UDT got CHAR
00932. 00000 - "inconsistent datatypes: expected %s got %s"
*Cause:    
*Action:
Error at Line: 96 Column: 47
I have been looking on OTN, Google ... every where I can think of. I am missing somthing simple or it is not possible I have not found documentation either way. Found one reference which was close to what I am doing. However the link to the explanation was broken ( Oracle Forums link ).
I have created a simple example below.
PS. Please no comment on using system ( i know :) ) this is a scratch database.
16:53:49 SQL> CREATE OR REPLACE TYPE system.MY_TYPE;
16:54:02 2 /
Type created.
16:54:04 SQL> CREATE OR REPLACE TYPE system.MY_TYPE_LIST AS TABLE OF REF system.MY_TYPE;
16:54:11 2 /
Type created.
16:54:13 SQL> CREATE OR REPLACE TYPE system.MY_TYPE AS OBJECT
16:54:27 2 ( COLUMN1 VARCHAR2(30),
16:54:35 3 SUB_LIST system.MY_TYPE_LIST
16:54:45 4 );
16:54:52 5 /
Type created.
16:54:55 SQL>
16:54:55 SQL> select system.my_type( tc.column_name, null ) from dba_tab_columns tc where tc.owner='SYS' and tc.table_name='DBA_TABLES';
--Should be noted there are no errors occured here* 16:56:00 SQL>
16:57:57 SQL> select system.my_type(
16:59:14 2 v.view_name,
16:59:20 3 cast( multiset (
16:59:26 4 select
16:59:31 5 tc.column_name,
16:59:36 6 null
16:59:45 7 from dba_tab_columns tc
16:59:51 8 where tc.table_name=v.view_name
16:59:56 9 and tc.owner=v.owner ) as system.my_type_list ) )
17:00:01 10 from dba_views v
17:00:06 11 where v.view_name = 'DBA_TABLES';
tc.column_name,
ERROR at line 5:
ORA-00932: inconsistent datatypes: expected UDT got CHAR
17:00:14 SQL>

Answer 1

create or replace type t_lookuprec as object
(Select columns1,2,3,....100
FROM A, B, C, D, E
WHERE ROWNUM < 1);You are correct that you need to use CREATE TYPE to use the type in SQL.
However unless I am mistaken you appear to have invented your own syntax for CREATE TYPE, suggest you refer to Oracle documentation.