DBA 常用的几张表
    select * from sys.all_all_tables;
select *from sys.all_tab_cols;
select * from sys.all_tab_columns;
select username from dba_users;
select * from dba_data_files; 
select * from dba_objects; 
select * from dba_tables; 
select * from dba_sequences; 
select * from dba_views; 
select * from all_views; 
select * from dba_db_links;