查询需要回滚到指定时间的数据
select * from SYS_USER as of timestamp to_timestamp('2018-12-31 17:50:38', 'yyyy-mm-dd hh24:mi:ss');
开启可移动数据命令，执行完就可以回滚数据
alter table SYS_USER enable row movement;
回滚数据
flashback table SYS_USER to timestamp TO_TIMESTAMP('2018-12-31 17:50:38', 'yyyy-mm-dd hh24:mi:ss');