Oracle的基本操作-數(shù)據(jù)字典和動態(tài)性能視圖的介紹

三、數(shù)據(jù)字典和動態(tài)性能視圖的介紹

1. 數(shù)據(jù)庫的數(shù)據(jù)字典

 （1） DBA_   全庫所有的某種對象的數(shù)據(jù)字典
       只有系統(tǒng)用戶才有權限查詢
 （2） ALL_   當前用戶創(chuàng)建的對象 + 其他用戶授予當前用戶使用的對象
       當前用戶
 （3） USER_  當前用戶創(chuàng)建的對象
       當前用戶

操作實例：
解鎖一個用戶hr并改密碼
SQL> alter user hr account unlock;

User altered.

SQL> alter user hr identified by hr;

User altered.

在scott用戶下，查看hr用戶下的表
SQL> conn scott/scott;
Connected.
SQL> select * from hr.jobs;
select * from hr.jobs
                 *
ERROR at line 1:
ORA-00942: table or view does not exist        --報錯，表或視圖不存在

SQL> conn hr/hr
Connected.
SQL> grant select on jobs to scott;        --授予select權限

Grant succeeded.

SQL> insert into hr.jobs values('HR_REP','asdfasd',1232,5545);
insert into hr.jobs values('HR_REP','asdfasd',1232,5545)
               *
ERROR at line 1:
ORA-01031: insufficient privileges


在某個用戶下：以下語句是等效的：
select * from user_objects where object_type='TABLE';

=select * from user_tables;

2. 動態(tài)性能視圖

select * from v$session;
select * from v$process;


練習：在SYS用戶下查詢DBA_OBJECTS,但是在scott用戶下查不到的，授權查詢給scott，使scott能夠查詢這個數(shù)據(jù)字典

SQL> conn scott/scott;
Connected.
SQL> select * from dba_objects;
select * from dba_objects
              *
ERROR at line 1:
ORA-00942: table or view does not exist


SQL> conn /as sysdba
Connected.

SQL> grant select on dba_objects to scott;
Grant succeeded.