scott@TESTDB11>select * from dept;

    DEPTNO DNAME          LOC

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

        10 ACCOUNTING     NEW YORK

        20 RESEARCH       DALLAS

        30 SALES          CHICAGO

        40 OPERATIONS     BOSTON

--确定系统当前SCN

sys@TESTDB11>select current_scn from v$database;

CURRENT_SCN

-----------

    2530398

1 row selected.

--更新表

scott@TESTDB11>update dept set loc='LocD' where deptno = 40;

1 row updated.

scott@TESTDB11>commit;

Commit complete.       

--使用SCN查看数据的历史状态(使用undo数据)

scott@TESTDB11>select * from dept as of scn 2530398;

    DEPTNO DNAME          LOC

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

        10 ACCOUNTING     NEW YORK

        20 RESEARCH       DALLAS

        30 SALES          CHICAGO

        40 OPERATIONS     BOSTON

--使用时间查看数据的历史状态

scott@TESTDB11>select * from dept as of timestamp (systimestamp - 5/(24*60));

    DEPTNO DNAME          LOC

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

        10 ACCOUNTING     NEW YORK

        20 RESEARCH       DALLAS

        30 SALES          CHICAGO

        40 OPERATIONS     LocD

scott@TESTDB11>select * from dept as of timestamp (systimestamp - 10/(24*60));

    DEPTNO DNAME          LOC

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

        10 ACCOUNTING     NEW YORK

        20 RESEARCH       DALLAS

        30 SALES          CHICAGO

        40 OPERATIONS     BOSTON

--使用时间间隔来指定时间

scott@TESTDB11>select * from dept as of timestamp (systimestamp - interval '150' minute);

    DEPTNO DNAME          LOC

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

        10 ACCOUNTING     NEW YORK

        20 RESEARCH       DALLAS

        30 SALES          CHICAGO

        40 OPERATIONS     BOSTON