In which SQL?

Each vendor has its own TZ implementation or does not handle it.

The few I know:

Oracle (9) has a handy function:
— from utc to pst
SELECT NEW_TIME( to_date(’10-MAR-05 00:01:02′,’DD-MON-YY HH24:MI:SS’), ‘GMT’, ‘PST’) from dual;
— from East Daylight saving time to Pacific Std Time
SELECT NEW_TIME( to_date(’10-MAR-05 00:01:02′,’DD-MON-YY HH24:MI:SS’), ‘EDT’, ‘PST’) from dual;

09-Mar-05 16:01:02
09-Mar-05 20:01:02

MS-SQL (2000):
<Quote>Note that the SQL Server datetime data type does not use timezone and has a smaller precision than the XML time data type. To include the timezone data type or additional precision, store the data in SQL Server 2000 using a string type.</Quote>
GETUTCDATE() returns the current UTC time.

Postgresql (8):

FUCNTION: to_timestamp(text, text)
RETURNS: <timestamp with time zone>
DESC.: convert string to time stamp

SELECT to_timestamp( ’10-MAR-05 00:01:02 UTC’,’DD-MON-YY HH24:MI:SS TZ’)

Doc chapter: 9.9.3. AT TIME ZONE
FUNCTION: AT TIME ZONE
<timestamp without time zone> AT TIME ZONE <zone >
RETURNS <timestamp with time zone>
DESC.: Convert local time in given time zone to UTC

<timestamp with time zone> AT TIME ZONE <zone>
RETURNS: timestamp without time zone
DESC.: Convert UTC to local time in given time zone

<time with time zone> AT TIME ZONE <zone>
RETURNS: <time with time zone>
DESC.: Convert local time across time zones

Philippe.