select * from dba_source as of timestamp sysdate-1/12解决方案

select * from dba_source as of timestamp sysdate-1/12
as   of   timestamp   sysdate-1/12     这是什么用法

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是FLASHBACK QUERY

9i以后提供的功能，功能是查询以前某时刻的表的数据
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查询2个小时之前，该表的数据状态
flashquery闪回查询
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as of timestamp sysdate-1/12 看不懂，
如果要查表t5001 的昨天的sql 操作如何写语句？
select * from t5001 as of timestamp sysdate-1/12