Query to find dropped users in database

Question

Hi i have requirement to drop all invalid objects in database where user no longer exists in database, it is documented by oracle that if a cascade drop is performed on a userid that objects like MV & synonyms etc.. will become INVALID but will not be dropped from database.
Anybody has any idea how we can find such INVALID objects of users whose id is dropped from database.
Appreciate your help in advance.
Thanks
Abhinay

Answer 1

It is documented that when you issue DROP USER some_user CASCADE user and all objects owned by that user are dropped. And if object is dropped it simply doesn't exist and therefore can be neither VALID nor INVALID. Unless you are talking about objects owned by some other user that is referencing dropped user object. Something like:
SQL> create user u1 identified by u1 default tablespace users quota unlimited on users;
User created.
SQL> create user u2 identified by u2 default tablespace users quota unlimited on users;
User created.
SQL> create table u1.tbl as select * from dual;
Table created.
SQL> grant select on u1.tbl to u2;
Grant succeeded.
SQL> create view u2.u1_tbl_vw as select * from u1.tbl;
View created.
SQL> select object_name,object_type,status from dba_objects where owner = 'U2';
OBJECT_NAME     OBJECT_TYPE             STATUS
U1_TBL_VW       VIEW                    VALID
SQL> drop user u1 cascade;
User dropped.
SQL> select object_name,object_type,status from dba_objects where owner = 'U2';
OBJECT_NAME     OBJECT_TYPE             STATUS
U1_TBL_VW       VIEW                    INVALID
SQL>
Then you have to query DBA_DEPENDENCIES before dropping the user:
SQL> create user u1 identified by u1 default tablespace users quota unlimited on users;
User created.
SQL> create user u2 identified by u2 default tablespace users quota unlimited on users;
User created.
SQL> create table u1.tbl as select * from dual;
Table created.
SQL> grant select on u1.tbl to u2;
Grant succeeded.
SQL> create view u2.u1_tbl_vw as select * from u1.tbl;
View created.
SQL> column owner format a10
SQL> column name format a10
SQL> select owner,name,type from dba_dependencies where referenced_owner = 'U1';
OWNER      NAME       TYPE
U2         U1_TBL_VW  VIEW
SQL>
SY.