日常我们可能需要限制一些客户端或者IP 访问某个用户 则可以通过trigger的方式实现 ##1.trigger内容 这边通过建立一个Trigger来限制登陆 ``` CREATE OR REPLACE TRIGGER global_logon_trg AFTER logon ON DATABASE DECLARE p_session_user varchar2(64); p_ip varchar2(64); BEGIN SELECT UPPER(SYS_CONTEXT('USERENV', 'SESSION_USER')) INTO p_session_user FROM DUAL; SELECT UPPER(SYS_CONTEXT('USERENV', 'IP_ADDRESS')) INTO p_ip FROM DUAL; DBMS_SESSION.SET_IDENTIFIER(p_session_user || '-' || p_ip); IF ((p_session_user = 'FWASSY') AND (p_ip IN ('10.65.5.189'))) THEN DBMS_SESSION.SET_IDENTIFIER('about to raise app_error..'); RAISE_APPLICATION_ERROR(-20003,'You are not allowed to connect to the database'); END IF; END; / ``` ##2. SYS_CONTEXT 如下为一些可用的参数,大家可以根据需求来进行指定 ```pythpn select SYS_CONTEXT('USERENV','TERMINAL') terminal, SYS_CONTEXT('USERENV','LANGUAGE') language, SYS_CONTEXT('USERENV','SESSIONID') sessionid, SYS_CONTEXT('USERENV','INSTANCE') instance, SYS_CONTEXT('USERENV','ENTRYID') entryid, SYS_CONTEXT('USERENV','ISDBA') isdba, SYS_CONTEXT('USERENV','NLS_TERRITORY') nls_territory, SYS_CONTEXT('USERENV','NLS_CURRENCY') nls_currency, SYS_CONTEXT('USERENV','NLS_CALENDAR') nls_calendar, SYS_CONTEXT('USERENV','NLS_DATE_FORMAT') nls_date_format, SYS_CONTEXT('USERENV','NLS_DATE_LANGUAGE') nls_date_language, SYS_CONTEXT('USERENV','NLS_SORT') nls_sort, SYS_CONTEXT('USERENV','CURRENT_USER') current_user, SYS_CONTEXT('USERENV','CURRENT_USERID') current_userid, SYS_CONTEXT('USERENV','SESSION_USER') session_user, SYS_CONTEXT('USERENV','SESSION_USERID') session_userid, SYS_CONTEXT('USERENV','PROXY_USER') proxy_user, SYS_CONTEXT('USERENV','PROXY_USERID') proxy_userid, SYS_CONTEXT('USERENV','DB_DOMAIN') db_domain, SYS_CONTEXT('USERENV','DB_NAME') db_name, SYS_CONTEXT('USERENV','HOST') host, SYS_CONTEXT('USERENV','OS_USER') os_user, SYS_CONTEXT('USERENV','EXTERNAL_NAME') external_name, SYS_CONTEXT('USERENV','IP_ADDRESS') ip_address, SYS_CONTEXT('USERENV','NETWORK_PROTOCOL') network_protocol, SYS_CONTEXT('USERENV','BG_JOB_ID') bg_job_id, SYS_CONTEXT('USERENV','FG_JOB_ID') fg_job_id, from dual ; ``` ##3.注意事项 - 该trigger对sys用户不生效 - 对具有dba权限的用户不生效