053第383题

383.At the request of a user, you issue the following command to restore a dropped table: flashback table
"BIN$F2JFfMq8Q5unbC0ceE9eJg==$0" to before drop; Later, the user notifies you that the data in the
table seems to be very old and out of date.
What might be the problem?
A. Because a proper range of SCNs was not specified, the wrong data was restored.
B. A proper range of timestamps was not specified, so the wrong data was restored.
C. A previous Flashback Drop operation had been performed, resulting in multiple versions of the table
being stored in the Recycle Bin.
D. Either option A or B could be correct. Not enough information was provided to determine which.
E. None of the above.
Answer: E

原题答案是E。有的版本号答案选C。个人认为正确答案是E

首先flashback drop 命令中没有指定SCN或者TIMESTAMP的选项，所以ABD不正确，然后FLASHBACK DROP命令不会在RECYCLE BIN里面创建对象，所以C不正确。

当处理回收站里面有多个同样original name的对象时。能够使用 对象在回收站中的名字(unique name)，如题目中所看到的。本题目中最可能的原因是DBA对 recycle bin中的对象drop time 推断错误，进而导致使用了错误的unique name.

You can also retrieve any table from the recycle bin, regardless of any collisions among original names, by using the unique recycle bin name of the table. For example, assume that you query the recycle bin as follows (sample output included):

SELECT object_name, original_name, createtime 
FROM   recyclebin;    

OBJECT_NAME                    ORIGINAL_NAME   CREATETIME
------------------------------ --------------- -------------------
BIN$yrMKlZaLMhfgNAgAIMenRA==$0 TEMP_EMPLOYEES  2007-02-05:21:05:52
BIN$yrMKlZaVMhfgNAgAIMenRA==$0 TEMP_EMPLOYEES  2007-02-05:21:25:13
BIN$yrMKlZaQMhfgNAgAIMenRA==$0 TEMP_EMPLOYEES  2007-02-05:22:05:53

You can use the following command to retrieve the middle table:

FLASHBACK TABLE BIN$yrMKlZaVMhfgNAgAIMenRA==$0 TO BEFORE DROP;

參考：http://docs.oracle.com/cd/E11882_01/backup.112/e10642/rcmflash.htm#BRADV81330