如何使用触发器实现数据库级守护,防止DDL操作

	如何使用触发器实现数据库级守护,防止DDL操作 --对于重要对象,实施DDL拒绝,防止create,drop,truncate,alter等重要操作 Last Updated: Sunday, 2004-10-31 12:06 Eygle
		不管是有意还是无意的,你可能会遇到数据库中重要的数据表等对象被drop掉的情况,这可能会给我们带来巨大的损失. 通过触发器，我们可以实现对于表等对象的数据库级守护，禁止用户drop操作. 以下是一个简单的范例，供参考: REM this script can be used to monitor a object REM deny any drop operation on it. CREATE OR REPLACE TRIGGER trg_dropdeny BEFORE DROP ON DATABASE BEGIN IF LOWER (ora_dict_obj_name ()) = 'test' THEN raise_application_error (num => -20000, msg => '你疯了,想删除表 ' || ora_dict_obj_name () || ' ?!!!!!' || '你完了，警察已在途中.....' ); END IF; END; / 测试效果:   SQL> connect scott/tiger Connected. SQL> create table test as select * from dba_users; Table created. SQL> connect / as sysdba Connected. SQL> create or replace trigger trg_dropdeny 2 before drop on database 3 begin 4 if lower(ora_dict_obj_name()) = 'test' 5 then 6 raise_application_error( 7 num => -20000, 8 msg => '你疯了,想删除表 ' || ora_dict_obj_name() || ' ?!!!!!' ||'你完了，警察已在途中.....'); 9 end if; 10 end; 11 / Trigger created. SQL> connect scott/tiger Connected. SQL> drop table test; drop table test * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-20000: 你疯了,想删除表 TEST ?!!!!!你完了，警察已在途中..... ORA-06512: at line 4   Oracle从Oracle8i开始,允许实施DDL事件trigger，可是实现对于DDL的监视及控制,以下是一个进一步的例子: create or replace trigger ddl_deny before create or alter or drop or truncate on database declare l_errmsg varchar2(100):= 'You have no permission to this operation'; begin if ora_sysevent = 'CREATE' then raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); elsif ora_sysevent = 'ALTER' then raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); elsif ora_sysevent = 'DROP' then raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); elsif ora_sysevent = 'TRUNCATE' then raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); end if; exception when no_data_found then null; end; /   我们看一下效果: [oracle@jumper tools]$ sqlplus "/ as sysdba" SQL*Plus: Release 9.2.0.4.0 - Production on Sun Oct 31 11:38:25 2004 Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved. Connected to: Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production With the Partitioning option JServer Release 9.2.0.4.0 - Production SQL> set echo on SQL> @ddlt SQL> create or replace trigger ddl_deny 2 before create or alter or drop or truncate on database 3 declare 4 l_errmsg varchar2(100):= 'You have no permission to this operation'; 5 begin 6 if ora_sysevent = 'CREATE' then 7 raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); 8 elsif ora_sysevent = 'ALTER' then 9 raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); 10 elsif ora_sysevent = 'DROP' then 11 raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); 12 elsif ora_sysevent = 'TRUNCATE' then 13 raise_application_error(-20001, ora_dict_obj_owner || '.' || ora_dict_obj_name || ' ' || l_errmsg); 14 end if; 15 16 exception 17 when no_data_found then 18 null; 19 end; 20 / Trigger created. SQL> SQL> SQL> connect scott/tiger Connected. SQL> create table t as select * from test; create table t as select * from test * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-20001: SCOTT.T You have no permission to this operation ORA-06512: at line 5 SQL> alter table test add (id number); alter table test add (id number) * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-20001: SCOTT.TEST You have no permission to this operation ORA-06512: at line 7 SQL> drop table test; drop table test * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-20001: SCOTT.TEST You have no permission to this operation ORA-06512: at line 9 SQL> truncate table test; truncate table test * ERROR at line 1: ORA-00604: error occurred at recursive SQL level 1 ORA-20001: SCOTT.TEST You have no permission to this operation ORA-06512: at line 11   我们可以看到,ddl语句都被禁止了,如果你不是禁止,可以选择把执行这些操作的用户及时间记录到另外的临时表中.以备查询.       本文作者: eygle,Oracle技术关注者,来自中国最大的Oracle技术论坛itpub. www.eygle.com是作者的个人站点.你可通过[email protected]来联系作者.欢迎技术探讨交流以及链接交换. 原文出处: http://www.eygle.com/faq/Use.Trigger.To.implement.ddl.deny.htm   如欲转载,请注明作者与出处.并请保留本文的连接. 回首页