首先查出当前的SCN

select dbms_flashback.get_system_change_number from dual
GET_SYSTEM_CHANGE_NUMBER
------------------------
               121211360

接下来就可以执行以下语句进行恢复了，注意下面语句的SCN值要小于上面查出的值如果值比上面小 还是没有恢复，继续调小SCN的值，直到恢复数据
insert into plan_voucher select * from plan_voucher as of scn 121210000;