How can I check a type's dependents order to drop them and replace/modify the initial type?

Question

I tried to modify a type using the following code and it gave me the error code: 'ORA-02303'. I don't know much about Oracle or PL/SQL but I need to solve this; so I'd appreciate any further help with this.

Thanks in advance. The code is just an example. But then again, I need to check its dependents first.

create or replace type A as object (
  x_ number, 
  y_ varchar2(10),
  member procedure to_upper
);
/

Answer 1

Look in DBA_DEPENDENCIES, ALL_DEPENDENCIES, or USER_DEPENDENCIES as appropriate:

SELECT OWNER, NAME, TYPE
  FROM DBA_DEPENDENCIES 
 WHERE REFERENCED_OWNER = [type owner]
   AND REFERENCED_NAME  = [type name]
   AND REFERENCED_TYPE  = 'TYPE'
/

Answer 2

Do not use DROP with FORCE, as it will automatically modify tables (delete columns) and god know what else to validate everything. Use something like:

ALTER TYPE type_name DROP ATTRIBUTE attr_name INVALIDATE;
ALTER TYPE type_name ADD ATTRIBUTE attr_name varchar2(50) CASCADE;

This will work on types with table/type dependencies.