Oracle USERENVºÍsys_context

1.USEREVN()
·µ»Øµ±Ç°Óû§»·¾³µÄÐÅÏ¢,opt¿ÉÒÔÊÇ:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE
1.ISDBA   ²é¿´µ±Ç°Óû§ÊÇ·ñÊÇDBAÈç¹ûÊÇÔò·µ»Øtrue
SQL> select userenv('isdba') from dual;
USEREN
------
FALSE
2.SESSION ·µ»Ø»á»°±êÖ¾
SQL> select userenv('sessionid') from dual;
USERENV('SESSIONID')
--------------------
                  152
4.ENTRYID ·µ»Ø»á»°ÈË¿Ú±êÖ¾
SQL> select userenv('entryid') from dual;
USERENV('ENTRYID')
------------------
                  0
5.INSTANCE ·µ»Øµ±Ç°INSTANCEµÄ±êÖ¾
SQL> select userenv('instance') from dual;
USERENV('INSTANCE')
-------------------
                   1
6.LANGUAGE ·µ»Øµ±Ç°»·¾³±äÁ¿
SQL> select userenv('language') from dual;
USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK
7.LANG ·µ»Øµ±Ç°»·¾³µÄÓïÑÔµÄËõд
SQL> select userenv('lang') from dual;
USERENV('LANG')
----------------------------------------------------
ZHS
8.TERMINAL ·µ»ØÓû§µÄÖն˻ò»úÆ÷µÄ±êÖ¾
SQL> select userenv('terminal') from dual;
USERENV('TERMINA
----------------
GAO
9.VSIZE(X) ·µ»ØXµÄ´óС(×Ö½Ú)Êý
SQL> select vsize(user),user from dual;
VSIZE(USER) USER
----------- ------------------------------
           6 SYSTEM
2.sys_context
¡¡¡¡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('U