Oracle 11g 新特性 只读表(readonly table)说明



一.Read only table说明

     在Oracle 11g之前,如果我们想要对一个表设置为只读的,可以通过授予某些用户select 权限。 但是对于表的所有者来说,还是读写的。

    在Oracle 11g中,我们可以直接对表的读写权限进行设置:

        ALTER TABLE table_name READ ONLY;

        ALTER TABLE table_name READ WRITE;

二.示例

--创建表

SQL> create table dave as select * fromdba_objects;

Table created.

--设置为只读:

SQL> alter table dave read only;

Table altered.

--查看表状态:

SQL> select table_name,status,read_onlyfrom dba_tables where table_name='DAVE';

TABLE_NAME                     STATUS   REA

------------------------------ -------- ---

DAVE                           VALID    YES

--这里显示是只读的。

--对Dave表进行DML操作:

SQL> insert into dave select * fromdave;

insert into dave select * from dave

           *

ERROR at line 1:

ORA-12081: update operation not allowed ontable "SYS"."DAVE"

SQL> update dave set object_id=88;

update dave set object_id=88

      *

ERROR at line 1:

ORA-12081: update operation not allowed ontable "SYS"."DAVE"

SQL> delete from dave;

delete from dave

           *

ERROR at line 1:

ORA-12081: update operation not allowed ontable "SYS"."DAVE"

SQL> truncate table dave;

truncate table dave

               *

ERROR at line 1:

ORA-12081: update operation not allowed ontable "SYS"."DAVE"

SQL> alter table dave add(namevarchar(20));

alter table dave add(name varchar(20))

*

ERROR at line 1:

ORA-12081: update operation not allowed ontable "SYS"."DAVE"

--虽然表示只读的,但是我们对表进行与索引相关的操作,因为索引修改的是数据字典,和表不相关。

SQL> create index idx_id on dave(object_id);

Index created.

SQL> drop index idx_id;

Index dropped.

--将表改成读写:

SQL> altertable dave read write;

Table altered.

SQL> droptable dave;

Table dropped.

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原文地址:https://www.cnblogs.com/tianlesoftware/p/3609143.html