Oracle Database Discussions

I use the following command to drop the tablespace:

drop tablespace users including contents and datafiles;

The error message is below:

Error report:
SQL Error: ORA-00604: error occurred at recursive SQL level 1
ORA-02429: cannot drop index used for enforcement of unique/primary key
00604. 00000 -  "error occurred at recursive SQL level %s"
*Cause:    An error occurred while processing a recursive SQL statement
           (a statement applying to internal dictionary tables).
*Action:   If the situation described in the next error on the stack
           can be corrected, do so; otherwise contact Oracle Support.

However, I have removed all the tables and indexes in this tablespace.

Nothing found when I issued the following enquiries.

select index_name from user_indexes where TABLESPACE_NAME = 'USERS';
select table_name from user_tables where TABLESPACE_NAME = 'USERS';

Is there anything I missed?


Thanks in advance.