OCP-1Z0-053-V12.02-56题

56.You discover that your Recycle Bin contains two tables with the same name, MY_TABLE. You also

have a table named MY_TABLE in your schema. You execute the following statement:

FLASHBACK TABLE my_table TO BEFORE DROP RENAME TO my_table2;

What will be the result of executing this statement?

A. One of the tables is recovered from the Recycle Bin using a First In First Out (FIFO) approach.

B. One of the tables is recovered from the Recycle Bin using a Last In First Out (LIFO) approach.

C. Both the tables are recovered from the Recycle Bin with one table renamed to MY_TABLE2 and the

other to a system-generated name.

D. None of the tables are recovered from the Recycle Bin, and the statement returns an error.

Answer: B

答案解析：

参考：http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_9012.htm#SQLRF54996

At the completion of the Flashback Table operation, the data in table is consistent with table at the earlier time. However, FLASHBACK TABLE TO SCN or TIMESTAMPdoes not preserve rowids, and FLASHBACK TABLE TO BEFORE DROP does not recover referential constraints.

参考：http://docs.oracle.com/cd/E11882_01/server.112/e25494/tables.htm#ADMIN11683

Restoring Tables from the Recycle Bin

Use the FLASHBACK TABLE ... TO BEFORE DROP statement to recover objects from the recycle bin. You can specify either the name of the table in the recycle bin or the original table name. An optional RENAME TO clause lets you rename the table as you recover it. The recycle bin name can be obtained from either the DBA_or USER_RECYCLEBIN view as shown in "Viewing and Querying Objects in the Recycle Bin". To use the FLASHBACK TABLE ... TO BEFORE DROP statement, you need the same privileges required to drop the table.

The following example restores int_admin_emp table and assigns to it a new name:

FLASHBACK TABLE int_admin_emp TO BEFORE DROP

   RENAME TO int2_admin_emp;

The system-generated recycle bin name is very useful if you have dropped a table multiple times. For example, suppose you have three versions of theint2_admin_emp table in the recycle bin and you want to recover the second version. You can do this by issuing two FLASHBACK TABLE statements, or you can query the recycle bin and then flashback to the appropriate system-generated name, as shown in the following example. Including the create time in the query can help you verify that you are restoring the correct table.

SELECT object_name, original_name, createtime FROM recyclebin;   

 

OBJECT_NAME                    ORIGINAL_NAME   CREATETIME

------------------------------ --------------- -------------------

BIN$yrMKlZaLMhfgNAgAIMenRA==$0 INT2_ADMIN_EMP  2006-02-05:21:05:52

BIN$yrMKlZaVMhfgNAgAIMenRA==$0 INT2_ADMIN_EMP  2006-02-05:21:25:13

BIN$yrMKlZaQMhfgNAgAIMenRA==$0 INT2_ADMIN_EMP  2006-02-05:22:05:53

 

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