select * from dba_views v where v.owner='SYS' and v.view_name='DBA_USERS';
select * from dba_tables t where t.table_name='USER$' and t.owner='SYS';
select * from dba_views v where v.owner='SYS' and v.view_name='DBA_ALERT_HISTORY';
select * from dba_tables t where t.table_name='WRI$_ALERT_HISTORY' and t.owner='SYS';
select * from dba_tables t where t.table_name like 'WR%$%' order by 2 ;