oracle如何记录用户的登陆信息

oracle如何记录用户的登陆信息
可以做一个触发器  
  用以下的方式可以监控登入登出的用戶:
创建一张记录登录TABLE，如下： 
CREATE TABLE SYSTEM.LOGIN_LOG
(
    SESSION_ID                     NUMBER(8,0) NOT NULL,
    LOGIN_ON_TIME                  DATE,
    LOGIN_OFF_TIME                 DATE,
    USER_IN_DB                     VARCHAR2(50),
    MACHINE                        VARCHAR2(50),
    IP_ADDRESS                     VARCHAR2(20),
    RUN_PROGRAM                    VARCHAR2(50)
)
PCTFREE 10
PCTUSED 40
MAXTRANS 255
TABLESPACE SYSTEM
STORAGE(INITIAL 64K MINEXTENTS 1 MAXEXTENTS 2147483645 FREELISTS 1 FREELIST GROUPS 1 BUFFER_POOL DEFAULT)
NOCACHE
LOGGING
/
COMMENT ON TABLE SYSTEM.LOGIN_LOG IS '登录日志'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.SESSION_ID IS 'sessionid'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.LOGIN_ON_TIME IS '登录时间'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.LOGIN_OFF_TIME IS '登出时间'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.USER_IN_DB IS '登录的DB User'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.MACHINE IS '机器名'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.IP_ADDRESS IS 'IP地址'
/
COMMENT ON COLUMN SYSTEM.LOGIN_LOG.RUN_PROGRAM IS '接入程序'
/
再创建