select * from v$database; 
select name from v$database; 
desc v$databases; 查看數據庫結構字段

SQL>select * from V_$PWFILE_USERS; 
Show user;查看當前數據庫連接用戶

select * from v$instance；

SQL> select TABLE_NAME from all_tables; 
select * from all_tables; 
SQL> select table_name from all_tables where table_name like '%u%'; 
TABLE_NAME 
------------------------------ 
_default_auditing_options_ 

desc CQI.T_BBS_XUSER;

select * from CQI.T_BBS_XUSER;

create user test11 identified by test default tablespace users Temporary TABLESPACE Temp;

grant connect,resource,dba to test11; 
grant sysdba to test11; 
commit; 

alter user sys indentified by test; 
alter user system indentified by test;