SQL> create table test(i int);

Table created

对象的 LAST_DDL_TIME：

SQL> select aa.OBJECT_NAME,to_char(aa.LAST_DDL_TIME,'yyyy-mm-dd hh24:mi:ss')  from user_objects aa where aa.OBJECT_NAME='TEST'

  2  ;

OBJECT_NAME                                                                      TO_CHAR(AA.LAST_DDL_TIME,'YYYY

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

TEST                                                                             2011-11-08 15:23:42

SQL> SELECT COUNT(*) FROM TEST;

  COUNT(*)

----------

         0

验证sql的执行计划：

SQL>

SQL> select aa.SQL_TEXT,aa.LAST_LOAD_TIME,aa.LAST_ACTIVE_TIME from v$sql aa

  2    where upper(aa.SQL_TEXT) like '%SELECT COUNT(*) FROM TEST%'

  3  ;

SQL_TEXT                                                                         LAST_LOAD_TIME                                            LAST_ACTIVE_TIME

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

 select aa.SQL_TEXT,aa.LAST_LOAD_TIME,aa.LAST_ACTIVE_TIME from v$sql aa   where  2011-11-08/15:26:24                                       2011-11-8 15:26:

 SELECT COUNT(*) FROM TEST                                                       2011-11-08/15:26:03                                     2011-11-8 15:26:

执行 comment操作：

SQL>  comment on column TEST.i is 'test';

Comment added

对象的 LAST_DDL_TIME：

SQL> select aa.OBJECT_NAME,to_char(aa.LAST_DDL_TIME,'yyyy-mm-dd hh24:mi:ss')  from user_objects aa where aa.OBJECT_NAME='TEST';

OBJECT_NAME                                                                      TO_CHAR(AA.LAST_DDL_TIME,'YYYY

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

TEST                                                                             2011-11-08 15:23:42

验证sql的执行计划是否还存在：

SQL> select aa.SQL_TEXT,aa.LAST_LOAD_TIME,aa.LAST_ACTIVE_TIME from v$sql aa

  2  where upper(aa.SQL_TEXT) like '%SELECT COUNT(*) FROM TEST%';

SQL_TEXT                                                                         LAST_LOAD_TIME                                            LAST_ACTIVE_TIME

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

 select aa.SQL_TEXT,aa.LAST_LOAD_TIME,aa.LAST_ACTIVE_TIME from v$sql aa   where  2011-11-08/15:26:24                                       2011-11-8 15:26:

 select aa.SQL_TEXT,aa.LAST_LOAD_TIME,aa.LAST_ACTIVE_TIME from v$sql aa where up 2011-11-08/15:27:42                                       2011-11-8 15:27:

 SELECT COUNT(*) FROM TEST                                                       2011-11-08/15:26:03                                       2011-11-8 15:26:

版本：

SQL> select * from v$version;

BANNER

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

Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production

PL/SQL Release 11.2.0.3.0 - Production

CORE    11.2.0.3.0      Production

TNS for Linux: Version 11.2.0.3.0 - Production

NLSRTL Version 11.2.0.3.0 - Production