scott@ORCL> create table tb_emp as select * from emp;      --基于emp表来创建表tb_emp

scott@ORCL> alter table tb_emp add constraint empno_pk     --添加主键约束,将产生主键索引

2  primary key(empno);

scott@ORCL> alter table tb_emp add constraint ename_uk     --添加唯一约束,将产生唯一索引

2  unique(ename);

scott@ORCL> alter table tb_emp add constraint sal_ck check(sal>0);     --添加check约束

scott@ORCL> alter table tb_emp modify job constraint job_nn not null;  --添加非空约束

scott@ORCL> alter table tb_emp add constraint dept_fk                  --添加外键约束

2  foreign key(deptno) references dept(deptno) on delete cascade;

scott@ORCL> select constraint_name,constraint_type           --查看tb_emp表上的所有约束

2  from user_constraints where table_name='TB_EMP';

CONSTRAINT_NAME C

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

EMPNO_PK        P

ENAME_UK        U

SAL_CK          C

JOB_NN          C

DEPT_FK         R

--下面查看表tb_emp所在文件的id,块的起始id,大小,以及该对象的对象id等

sys@ORCL> select file_id,block_id,bytes from dba_extents where segment_name='TB_EMP';

FILE_ID   BLOCK_ID      BYTES

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

4        393      65536

sys@ORCL> select object_name,object_id from dba_objects  --查看表tb_emp的对象ID

2  where object_name = 'TB_EMP';

OBJECT_NAME           OBJECT_ID

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

TB_EMP                    54493

--对表进行重命名

scott@ORCL> alter table tb_emp rename to tb_employees;

sys@ORCL> select file_id,block_id,bytes from dba_extents  --重命名后所在文件的id,块的起始id,大小没有发生变化

2  where segment_name='TB_EMPLOYEES';

FILE_ID   BLOCK_ID      BYTES

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

4        393      65536

sys@ORCL> select object_name,object_id from dba_objects  --重命名后对象ID没有发生变化

2  where object_name = 'TB_EMPLOYEES';

OBJECT_NAME           OBJECT_ID

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

TB_EMPLOYEES              54493

scott@ORCL> select index_name,index_type              --重命名后索引和约束也没有发生变化

2  from user_indexes where table_name='TB_EMPLOYEES'

3  union all

4  select constraint_name,constraint_type

5  from user_constraints where table_name='TB_EMPLOYEES';

INDEX_NAME                     INDEX_TYPE

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

EMPNO_PK                       NORMAL

ENAME_UK                       NORMAL

EMPNO_PK                       P

ENAME_UK                       U

SAL_CK                         C

JOB_NN                         C

DEPT_FK                        R

scott@ORCL> drop table tb_employees;

scott@ORCL> select object_name,original_name,can_undrop,

2  base_object from user_recyclebin;

OBJECT_NAME                    ORIGINAL_NAME                    CAN BASE_OBJECT

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

BIN$k1zC3yEiwZvgQAB/AQBRVw==$0 TB_EMPLOYEES                     YES 54493

BIN$k1zC3yEhwZvgQAB/AQBRVw==$0 ENAME_UK                         NO  54493

BIN$k1zC3yEgwZvgQAB/AQBRVw==$0 EMPNO_PK                         NO  54493

scott@ORCL> select count(1) from "BIN$k1zC3yEiwZvgQAB/AQBRVw==$0";  --可以使用回收站名来访问对象，但要对对象加双引号

COUNT(1)

----------

13

scott@ORCL> flashback table tb_employees to before drop;   --进行闪回

Flashback complete.

scott@ORCL> select count(1) from tb_employees;             --闪回后表存在并且可以访问

COUNT(1)

----------

13

scott@ORCL> select index_name,index_type                   --查看闪回后索引，约束的情况，发现其名称仍然为BIN$名称

2  from user_indexes where table_name='TB_EMPLOYEES'

3  union all

4  select constraint_name,constraint_type

5  from user_constraints where table_name='TB_EMPLOYEES';

INDEX_NAME                     INDEX_TYPE

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

BIN$k1zC3yEgwZvgQAB/AQBRVw==$0 NORMAL

BIN$k1zC3yEhwZvgQAB/AQBRVw==$0 NORMAL

BIN$k1zC3yEcwZvgQAB/AQBRVw==$0 P

BIN$k1zC3yEdwZvgQAB/AQBRVw==$0 U

BIN$k1zC3yEewZvgQAB/AQBRVw==$0 C

BIN$k1zC3yEfwZvgQAB/AQBRVw==$0 C

scott@ORCL> insert into tb_employees(empno,ename,job,sal,deptno)

2  select 9999,'Robinson','DBA',3000,50 from dual;

1 row created.      --可以成功插入，deptno列的外键约束已经被删除，故deptno为号成功插入

scott@ORCL> alter index "BIN$k1zC3yEgwZvgQAB/AQBRVw==$0" rename to EMPNO_PK;

Index altered.      --将BIN开头的索引改回原来的名字，其余的约束名修改在此省略

sys@ORCL> select tablespace_name,sum(bytes/1024/1024) ||' M'

2  from dba_free_space where tablespace_name='TBS1'

3  group by tablespace_name;     --表空间tbs1的可用空间为M

TABLESPACE_NAME                SUM(BYTES/1024/1024)||'M'

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

TBS1                           .9375 M

flasher@ORCL> create table tb1 tablespace tbs1 as select * from dba_objects

2  where rownum < 6000;

sys@ORCL> select tablespace_name,sum(bytes/1024/1024) ||' M'

2  from dba_free_space where tablespace_name='TBS1'

3  group by tablespace_name;  --在该表空间创建表tb1之后，可用空间为.25M

TABLESPACE_NAME                SUM(BYTES/1024/1024)||'M'

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

TBS1                           .25 M

flasher@ORCL> drop table tb1;   --将表tb1删除

flasher@ORCL> show recyclebin;  --删除后的对象位于回收站中

ORIGINAL NAME    RECYCLEBIN NAME                OBJECT TYPE  DROP TIME

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

TB1              BIN$k2oZsEiaG7LgQAB/AQAZMA==$0 TABLE        2010-10-25:12:05:18

flasher@ORCL> select object_name,original_name,can_undrop,

2  base_object from user_recyclebin;

OBJECT_NAME                    ORIGINAL_N CAN BASE_OBJECT

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

BIN$k2oZsEiaG7LgQAB/AQAZMA==$0 TB1        YES       54531

sys@ORCL> select tablespace_name,sum(bytes/1024/1024) ||' M'

2   from dba_free_space where tablespace_name='TBS1'

3   group by tablespace_name;   --表空间tbs1显示的可用空间已返还为1M

--但并不是真正为M,在需要表空间时,将自动清除回收站最老的对象,以满足当前空间需求

TABLESPACE_NAME                SUM(BYTES/1024/1024)||'M'

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

TBS1                           .9375 M

sys@ORCL> select tablespace_name,autoextensible   --这个查询可以看出表空间tbs1不能自动扩展

2  from dba_data_files where tablespace_name ='TBS1';

TABLESPACE_NAME AUT

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

TBS1            NO

flasher@ORCL> create table tb2 tablespace tbs1 as select * from dba_objects  --再次在表空间创建新表tb2

2  where rownum < 6000;

flasher@ORCL> show recyclebin;  --此时回收站中原来的表tb1记录被自动清除

flasher@ORCL> select object_name,original_name,can_undrop,

2  base_object from user_recyclebin;

no rows selected

flasher@ORCL> flashback table tb1 to before drop;  --此时表tb1不能被闪回

flashback table tb1 to before drop

*

ERROR at line 1:

ORA-38305: object not in RECYCLE BIN