怎么更改當前的USERENV('LANG')返回值

[php]
SQL> ALTER SESSION SET NLS_LANGUAGE='AMERICAN';

Session altered.

SQL> select USERENV('LANG') from dual;

USERENV('LANG')
----------------------------------------------------
US

SQL>  ALTER SESSION SET NLS_LANGUAGE='SIMPLIFIED CHINESE';

会话已更改。

SQL> select USERENV('LANG') from dual;

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

SQL>
[/php]