Oracle创建上下文 SYS_CONTEXT

Oracle创建上下文 SYS_CONTEXT

1. 系统默认的一些参数

set heading off
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,
       SYS_CONTEXT('USERENV', 'AUTHENTICATION_TYPE') authentication_type,
       SYS_CONTEXT('USERENV', 'AUTHENTICATION_DATA') authentication_data
  from dual;
-- 另一种展示方式
set serveroutput on
exec dbms_output.put_line(sys_context('USERENV','CURRENT_USER'));

2. 自定义上下文属性

create user king identified by king;
grant dba to king;
connect king/king
create table emp as select * from scott.emp;
create context emp_user using current_emp;
​
-- 创建包current_emp
CREATE OR REPLACE PACKAGE current_emp IS
  PROCEDURE set_emp_info;
END;
/

CREATE OR REPLACE PACKAGE BODY current_emp IS
  PROCEDURE set_emp_info IS
    v_sal      emp.sal%TYPE;
    v_job      emp.JOB%TYPE;
    v_hiredate emp.HIREDATE%TYPE;
  BEGIN
    SELECT sal, JOB, HIREDATE
      INTO v_sal, v_job, v_hiredate
      FROM emp
     WHERE ename = SYS_CONTEXT('USERENV', 'SESSION_USER');
 
    DBMS_SESSION.SET_CONTEXT('emp_user', 'sal', v_sal);
    DBMS_SESSION.SET_CONTEXT('emp_user', 'job', v_job);
    DBMS_SESSION.SET_CONTEXT('emp_user', 'hiredate', v_hiredate);
    DBMS_SESSION.SET_CONTEXT('emp_user', 'ename', SYS_CONTEXT('USERENV', 'SESSION_USER'));
  EXCEPTION
    WHEN NO_DATA_FOUND THEN
      NULL;
  END;
END;
/
​

 -- 创建触发器
CREATE or REPLACE TRIGGER emp_logon 
AFTER LOGON ON DATABASE 
BEGIN 
current_emp.set_emp_info; 
END; 
/ 
​
-- 验证
exit
sqlplus king/king
SET SERVEROUTPUT ON 
EXEC dbms_output.put_line(sys_context('emp_user', 'SAL')); 
EXEC dbms_output.put_line(sys_context('emp_user', 'job')); 
EXEC dbms_output.put_line(sys_context('emp_user', 'hiredate'));
SELECT sys_context('emp_user', 'SAL') FROM DUAL;
​
--列出当前session 的所有上下文属性
sqlplus king/king
​
SET ECHO OFF 
SET SERVEROUTPUT ON 
DECLARE
  list dbms_session.AppCtxTabTyp;
  cnt  number;
BEGIN
  dbms_session.list_context(list, cnt);
  IF cnt = 0 THEN
    dbms_output.put_line('No contexts active.');
  ELSE
    FOR i IN 1 .. cnt LOOP
      dbms_output.put_line(list(i).namespace || ' ' || list(i).attribute ||
                            ' = ' || list(i).value);
    END LOOP;
  END IF;
END;
/
​
--查询
SELECT * 
FROM dba_context 
WHERE namespace = 'EMP_USER'; 

参考

【诗檀学院】ORACLE 11g OCM考试学习材料-手动实操课程