CREATE OR REPLACE TRIGGER disablelogin                                      
        AFTER logon ON acgvm_2.schema    -->使用方式為username.schema           
    DECLARE                                                                     
        ipaddr VARCHAR2(30);                                                      
   BEGIN                                                                       
        SELECT sys_context('userenv', 'ip_address')                               
        INTO   ipaddr                                                             
        FROM   dual;                                                              
        IF ipaddr != '192.168.*.***' THEN   -->如果需要該IP地址也可以替換成萬用字元('192.168.*.%')                                        
            raise_application_error('-20001',                                       
                        'You can not login,Please contact administrator');                
        END IF;                                                                   
    END disablelogin;