USEREVN

返回当前用户环境的信息,opt可以是:
ENTRYID,SESSIONID,TERMINAL,ISDBA,LABLE,LANGUAGE,CLIENT_INFO,LANG,VSIZE

1.ISDBA 查看当前用户是否是DBA如果是则返回true
SQL> select userenv('isdba') from dual;

USEREN
------
FALSE

2.SESSION 返回会话标志

SQL> select userenv('sessionid') from dual;

USERENV('SESSIONID')
--------------------
152

4.ENTRYID 返回会话人口标志

SQL> select userenv('entryid') from dual;

USERENV('ENTRYID')
------------------
0

5.INSTANCE 返回当前INSTANCE的标志
SQL> select userenv('instance') from dual;

USERENV('INSTANCE')
-------------------
1

6.LANGUAGE 返回当前环境变量
SQL> select userenv('language') from dual;

USERENV('LANGUAGE')
----------------------------------------------------
SIMPLIFIED CHINESE_CHINA.ZHS16GBK

7.LANG 返回当前环境的语言的缩写
SQL> select userenv('lang') from dual;

USERENV('LANG')
----------------------------------------------------
ZHS

8.TERMINAL 返回用户的终端或机器的标志
SQL> select userenv('terminal') from dual;

USERENV('TERMINA
----------------
GAO

9.VSIZE(X) 返回X的大小(字节)数
SQL> select vsize(user),user from dual;

VSIZE(USER) USER
----------- ------------------------------
6 SYSTEM