Determining PST time from SYSTIMESTAMP

Question

Thanks to everyone who answered by previous question about SYSTIMESTAMP.
Here's a PL/SQL function I wrote to convert the current time to PST and return it as a DATE value. The idea is that it should work regardless of what the database's timezone is set to.
Any critiques are welcome - efficiency, style, whatever. In particular, is there a way to avoid the conversion to a VARCHAR2? Is there a system supplied function I am overlooking?
Thanks again!
CREATE OR REPLACE FUNCTION PST_SYSDATE RETURN DATE IS
  th NUMBER;
  tm NUMBER;
  now TIMESTAMP(6) WITH TIME ZONE;
  d  VARCHAR2(200);
BEGIN
  now := SYSTIMESTAMP;
  SELECT
    TO_CHAR(now, 'YYYY-MM-DD HH24:MI:SS'),
    EXTRACT(timezone_hour FROM now) TH,
    EXTRACT(timezone_minute FROM now) TM
  INTO d, th, tm
  FROM DUAL;
  RETURN TO_DATE(d, 'YYYY-MM-DD HH24:MI:SS') - ((th+tm/60+8)/24); 
END PST_SYSDATE;
/

Answer 1

You do not need a function for that. Use AT TIME ZONE TZ_OFFSET:
SQL> ALTER SESSION SET NLS_DATE_FORMAT = 'MM/DD/YYYY HH24:MI:SS'
  2  /
Session altered.
SQL> SELECT  SYSTIMESTAMP EST,
  2          SYSTIMESTAMP AT TIME ZONE TZ_OFFSET('PST') PST,
  3          CAST(SYSTIMESTAMP AT TIME ZONE TZ_OFFSET('PST') AS DATE) PST_DATE
  4    FROM  DUAL
  5  /
EST                                      PST                                      PST_DATE
08-APR-09 03.25.39.034000 PM -04:00      08-APR-09 12.25.39.034000 PM -07:00      04/08/2009 12:25:39
SQL> SY.