SQL: modify date type

SCOTT@HUIYI>select sysdate from dual;

SYSDATE
----------
13-1月 -07

SCOTT@HUIYI>alter session set nls_date_format = 'yyyy-mm-dd hh24:mi:ss';

已更改階段作業.

SCOTT@HUIYI>select sysdate from dual;

SYSDATE
-------------------
2007-01-13 13:31:06

SCOTT@HUIYI>select to_char(sysdate,'Day') from dual;

TO_CHA
------
星期六

-- 轉換中指定
SCOTT@HUIYI>select to_char(sysdate,'Day','nls_date_language=american') from dual;

TO_CHAR(S
---------
Saturday

SCOTT@HUIYI>

-- 更改SESSION
SCOTT@HUIYI>alter session set nls_date_language=american;

已更改階段作業.

SCOTT@HUIYI>select to_char(sysdate,'Day') from dual;

TO_CHAR(S
---------
Saturday

SCOTT@HUIYI>alter session set nls_date_language='simplified chinese';

已更改階段作業.

SCOTT@HUIYI>select to_char(sysdate,'Day') from dual;

TO_CHA
------
星期六

SCOTT@HUIYI>alter session set nls_date_language='TRADITIONAL CHINESE';

已更改階段作業.

SCOTT@HUIYI>select to_char(sysdate,'Day') from dual;

TO_CHA
------
星期六

SCOTT@HUIYI>

SCOTT@HUIYI>alter session set nls_date_language=american;

已更改階段作業.

SCOTT@HUIYI>select to_char(sysdate,'Day') from dual;

TO_CHAR(S
---------
Saturday

SCOTT@HUIYI>select to_char(sysdate,'Day','nls_date_language=''TRADITIONAL CHINESE''') from dual;

TO_CHA
------
星期六