在10g以前是没有这个功能的，删除后就没有了，只能从备份恢复。

＃将执行的操作记录在文件中，就是屏幕输出的内容
SQL>spool '/home/oracle/drop.txt'


＃＃删除 emp表
SQL> drop table emp ;

Table dropped.

＃现在查看emp已经不存在了
SQL> select * from emp ;
select * from emp
              *
ERROR at line 1:
ORA-00942: table or view does not exist

＃查看回收站的内容
SQL> show recyclebin
ORIGINAL NAME    RECYCLEBIN NAME                OBJECT TYPE  DROP TIME          
---------------- ------------------------------ ------------ -------------------
EMP              BIN$sGRMOtFvhCPgQKjABwAOsw==$0 TABLE        2011-10-29:06:20:34

＃查看用户回收站的内容
SQL> select * from user_recyclebin
  2  ;

OBJECT_NAME                    ORIGINAL_NAME                    OPERATION       
------------------------------ -------------------------------- ---------       
TYPE                      TS_NAME                        CREATETIME             
------------------------- ------------------------------ -------------------    
DROPTIME               DROPSCN PARTITION_NAME                   CAN CAN         
------------------- ---------- -------------------------------- --- ---         
   RELATED BASE_OBJECT PURGE_OBJECT      SPACE                                  
---------- ----------- ------------ ----------                                  
BIN$sGRMOtFvhCPgQKjABwAOsw==$0 EMP                              DROP            
TABLE                     USERS                          2005-06-30:19:47:57    
2011-10-29:06:20:34     517667                                  YES YES         
     51148       51148        51148          8                                  
                                                                                

OBJECT_NAME                    ORIGINAL_NAME                    OPERATION      
------------------------------ -------------------------------- ---------      
TYPE                      TS_NAME                        CREATETIME            
------------------------- ------------------------------ -------------------   
DROPTIME               DROPSCN PARTITION_NAME                   CAN CAN        
------------------- ---------- -------------------------------- --- ---        
   RELATED BASE_OBJECT PURGE_OBJECT      SPACE                                 
---------- ----------- ------------ ----------                                 
BIN$sGRMOtFuhCPgQKjABwAOsw==$0 PK_EMP                           DROP           
INDEX                     USERS                          2005-06-30:19:47:57   
2011-10-29:06:20:34     517663                                  NO  YES        
     51148       51148        51149          8                                 
                                                                               
将回收站的表恢复出来
SQL> flashback table emp to before drop ;

Flashback complete.

再看回收站就没有东西了
SQL> show recyclebin

emp现在又可以用了
SQL> select * from emp where sal > 3000;

     EMPNO ENAME      JOB              MGR HIREDATE         SAL       COMM     
---------- ---------- --------- ---------- --------- ---------- ----------     
    DEPTNO                                                                     
----------                                                                     
      7839 KING       PRESIDENT            17-NOV-81       5000                
        10                                                                     
                                                                               

SQL> spool off
[root@bogon oracle]#

相关知识点：
1、从回收站恢复时重命名表
SQL> flashback table t2 to before drop rename to t4 ;

2、删除回收站指定的表
SQL> purge table t4;

3、清空回收站
SQL> purge recyclebin

4、删除表时不经过回收站直接删除

SQL> drop table t3 purge ;