/*1.FLASHBACK QUERY*/
--闪回到15分钟前
select * from orders as of timestamp (systimestamp - interval ''15'' minute) where ......
这里可以使用DAY、SECOND、MONTH替换minute，例如：
SELECT * FROM orders AS OF TIMESTAMP(SYSTIMESTAMP - INTERVAL ''2'' DAY)
--闪回到某个时间点
select * from orders as of timestamp to_timestamp (''01-Sep-04 16:18:57.845993'', ''DD-Mon-RR HH24:MI:SS.FF'') where ...
--闪回到两天前
select * from orders as of timestamp (sysdate - 2) where.........
/*2.FLASHBACK DROP*/
1.flashback table orders to before drop;
2.如果源表已经重建，可以使用rename to子句：
flashback table order to before drop rename to order_old_version;
/*3.FLASHBACK TABLE*/
1.首先要启用行迁移：
alter table order enable row movement;
2.闪回表到15分钟前：
flashback table order to timestamp systimestamp - interval ''15'' minute;
闪回到某个时间点：
FLASHBACK TABLE order TO TIMESTAMP TO_TIMESTAMP('2007-09-12 01:15:25 PM','YYYY-MM-DD HH:MI:SS AM')