You are performing flashback of the ORDERS table in the Scott’s schema because some important data is deleted in the table by mistake. The SCN number was 771513 at the time of deletion. You issued the following statement to perform Flashback Table： 
SQL> FLASHBACK TABLE ORDERS TO SCN 771513；  
What is the prerequisite to perform Flashback Table？（）

You are working as a DBA at NetFx Corporation. A user， Scott， is maintaining the records of all the employees in the EMPLOYEEtable. Initially， the salary of the employee， ’E0025’， was $1800. On 1 May 2004， the salary of the employee， ’E0025’， was increased by $200.  
The user， Scott， issued the following statement to modify the record of the employee， ’E0025’：  
SQL>UPDATE EMPLOYEE  SET SALARY = 2000  
WHERE EMPNO = ’E0025’；  
SQL>COMMIT；  
On December 1， 2004， the salary of the employee， ’E0025’， was increased by $400. The user， Scott， issued the following statement to modify the record of the employee， ’E0025’：  
SQL>UPDATE EMPLOYEE  SET SALARY = 2400  
WHERE EMPNO = ’E0025’； 
 SQL>COMMIT；  
On July 1， 2005， the salary of the employee， ’E0025’， was increased by $500. The user， Scott， issued the following statement to modify the record of the employee， ’E0025’  
SQL>UPDATE EMPLOYEE  SET SALARY = 2900  
WHERE EMPNO = ’E0025’；  
SQL>COMMIT；  
On July 5， 2005， the HR manager asked you to generate the increment report of the employee， ’E0025’， for the period between 1 May 2004 and 1 July 2005. Which flashback feature will you use to generate the increment report？（）

You issued the following command：       
SQL> DROP TABLE MYTABLE；       
SQL> SHOW RECYCLEBIN  The following output is returned：  
     ORIGINAL NAME RECYCLEBIN NAME               OBJECT TYPE      DROP TIME       
------------- ------------------------------ --------------- --------------------       
MYTABLE BIN$04LhcpndanfgMAAAAAANPw==$0     TABLE          
2005-01-13：20：11：31  You want to drop the table， MYTABLE， from the Recycle Bin. Which two commands can you issue to accomplish the desired task？（）

You are working as a Database Administrator. You erroneously dropped an important table named WAREHOUSE_DETAILS. The table resides in a non-SYSTEM tablespace.  The following dependent objects have been defined on the dropped table：

  
  
Due to limited space， some of the indexes and triggers have been removed from the Recycle Bin. You decide to recover the table by using Flashback Drop. You execute the following statement： SQL>FLASHBACK TABLE warehouse_details TO BEFORE DROP；  
What will be the implication of executing this statement？（）

At 5：30 PM， a database administrator， William， is informed that an important record of employee no E0025 is missing from the SCOTT.EMPLOYEE table. At 4：30 P.M， the table contained the record of employee no E0025. William issues the following command to find the SQL statements that are used to undo the deletion：   
SELECT operation， undo_sql， logon_user  
FROM FLASHBACK_TRANSACTION_QUERY  WHERE xid=  
HEXTORAW（’0100043E23456’）；  
where ’0100043E23456’ is the transaction ID of the transaction that deleted the row. Before issuing the above statement， which task did William perform to identify the transaction ID of the transaction that deleted the row？（）