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select * from sys.smon_scn_time;
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select * from student as of scn 592258
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insert into student select * from student as of scn 592258 where id not in (select id from student)
select * from v$transaction ---ûÓÐÌá½»µÄÊÂÎñ¡£
select * from flashback_transaction_query; ---»Ø¹öÊÂÎñ¡£ ËûÓÐÒ»ÁÐÊÇ undo_sql µÃµ½Ëû¾Í¿ÉÒԻعö¸Õ²ÅÌá½»µÄÊÂÎñ¡£
select * from FLASHBACK_TRANSACTION_QUERY a
where a.start_timestamp between to_date('2008-12-7 14:40:56','yyyy-MM-dd HH24:mi:ss') and
to_date('2008-12-7 14:59:56','yyyy-MM-dd HH24:mi:ss');
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