oracle11G闪回flashback - 数据库编程

oracle11G闪回flashback oracle9i的闪回：

闪回查询从9i引入，可以按照时间点或者SCN向前查

询，获取修改前的数据。

闪回查询依赖于回滚段中存储的数据前镜像，通过设置

undo_retention参数设置前镜像的保留时间。

查询的语法：

select … as of scn | timestamp

Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 Connected as hr@JIAGULUN
SQL> select * from student; ID NAME AGE ----------- -------------------- ----------- 1 zhangsan 21 2 lisi 22 3 wangwu 23
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 17:58:58
SQL> SQL> update student s set s.name='mazi' where s.id = 1; 1 row updated
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 18:02:56
SQL> delete from student s where s.name = 'lisi'; 1 row deleted
SQL> select * from student; ID NAME AGE ----------- -------------------- ----------- 1 mazi 21 3 wangwu 23
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 18:04:00
SQL> delete from student; 2 rows deleted
SQL> select * from student; ID NAME AGE ----------- -------------------- -----------
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 18:04:26
SQL> select * from student as of scn 3099731; ID NAME AGE ----------- -------------------- ----------- 1 zhangsan 21 2 lisi 22 3 wangwu 23 SQL> select * from student; ID NAME AGE ----------- -------------------- -----------
SQL> commit; Commit complete
SQL> insert into student values(1,'zhangsan',23); 1 row inserted
SQL> commit; Commit complete
SQL> SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 19:36:30
SQL> SQL> delete from student; 1 row deleted
SQL> commit; Commit complete
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 19:36:51
SQL> select * from student as of timestamp to_date('20150124 19:36:30','yyyymmdd hh24:mi:ss'); ID NAME AGE ----------- -------------------- ----------- 1 zhangsan 23
SQL> select * from student as of timestamp to_date('20150124 18:04:26','yyyymmdd hh24:mi:ss'); ID NAME AGE ----------- -------------------- ----------- 1 zhangsan 21 2 lisi 22 3 wangwu 23
SQL>

oracle10g的闪回版本查询：

对于9i的闪回查询进行增强，Oracle10g提供了闪回版本

查询，因为9i的闪回查询仅仅能够得到过去某个时间点上的

数据，但是无法反映出一段时间内数据表中数据的变化，

10g的闪回版本查询可以对时间段内数据表的不同版本进行

查询。

闪回版本查询的语法：

select … from … versions between

其中，select后面可以选择伪列，来获得事务的开始、结束时间、SCN号、ID号等。

SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 19:40:11
SQL> select dbms_flashback.get_system_change_number from dual; GET_SYSTEM_CHANGE_NUMBER ------------------------使用上面的系统包必须赋予权限：grant execute on dbms_flashback to hr; 3115836
SQL> SQL> insert into student values(1,'zhangsan',23); 1 row inserted
SQL> commit; Commit complete
SQL> select to_char(sysdate,'yyyymmdd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YYYYMMDDHH24: ------------------------------ 20150124 19:51:36
SQL> select dbms_flashback.get_system_change_number from dual; GET_SYSTEM_CHANGE_NUMBER ------------------------ 3115938
SQL> upd

oracle11G闪回flashback(一)