【练习】flashback基于scn的闪回查询

1.创建表dept1：

13:01:03 SCOTT@ORA11GR2>create table dept1 as select * from dept;

Table created.

13:01:40 SCOTT@ORA11GR2>select * from dept1;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON

13:02:22 SCOTT@ORA11GR2>insert into dept1 values(50,‘xxx‘,‘xxxx‘);

1 row created.

2.查看当前的scn：

13:04:12 SYS@ORA11GR2>select current_scn from v$database;

CURRENT_SCN
-----------
    1006836

3.删除表dept1：

13:07:51 SCOTT@ORA11GR2>delete from dept1;

4 rows deleted.

13:08:03 SCOTT@ORA11GR2>select * from dept1;

no rows selected

4.基于scn的查询：

13:08:15 SCOTT@ORA11GR2>select * from dept1 as of scn 1006836;

    DEPTNO DNAME          LOC
---------- -------------- -------------
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
        50 xxx            xxxx