Synonyms pointing to non existing objects

Question

Hi,
How to find out the public/private synonyms pointing to the non existing objects.
Let us say, we have created synonyms for a few tables, 1 year back. A few days later, we have dropped the tables.
How to get the list of synonyms which do not have the base tables.
All replies are welcome
Thanks
DRK

Answer 1

Probably, you will still be having the list of dropped tables. To identify all the synonyms for the dropped tables we can query:
select * from user_synonyms where table_name in ('A', 'B', ....);
Once I identified you can drop these synonyms.
Alternatively, if you do not have the list of tables then (assuming you are on 10g), you could do something like this:
1) Identify all the synonyms with INVALID state and try to query/execute them.
2) Drop the one's which still remain INVALID (make sure they are referring the dropped tables)
SQL>  create table t (a number);
Table created.
SQL> create synonym st for t;
Synonym created.
SQL> select object_name, status from user_objects where object_name = 'ST';
OBJECT_NAME     STATUS
ST              VALID
SQL>
SQL>
SQL>
SQL>
SQL> drop table t purge;
Table dropped.
SQL> select object_name, status from user_objects where object_name = 'ST';
OBJECT_NAME     STATUS
ST              INVALID
SQL>Synonyms could still remain in INVALID state if any changes are made to the underlying tables, so executing the synonym again will return it to VALID state provided table still exists.
SQL>  create table t (a number);
Table created.
SQL> create synonym st for t;
Synonym created.
SQL> select object_name, status from user_objects where object_name = 'ST';
OBJECT_NAME     STATUS
ST              VALID
SQL> alter table t add (b number);
Table altered.
SQL> select object_name, status from user_objects where object_name = 'ST';
OBJECT_NAME     STATUS
ST              INVALID
SQL> select * from st;
no rows selected
SQL> select object_name, status from user_objects where object_name = 'ST';
OBJECT_NAME     STATUS
ST              VALID
SQL>