Example - Teradata Vantage - Analytics Database

Consider the following statements:

SET TIME ZONE INTERVAL '01:00' HOUR TO MINUTE;
SELECT CAST(TIMESTAMP '2008-05-31 22:30:00-08:00' 
   AS DATE AT SOURCE TIME ZONE);
SELECT TIMESTAMP '2008-06-01 06:30:00+00:00' AT '-08:00' 
   (DATE, AT SOURCE);
SELECT TIMESTAMP '2008-06-01 06:30:00+00:00' (DATE, AT -8);
SELECT TIMESTAMP '2008-06-01 07:30:00' (DATE, AT -8);

These SELECT statements return the date for time zone displacement, INTERVAL -'08:00' HOUR TO MINUTE; that is, the statements return '08/05/31'. If the SELECT statements were specified without an AT clause or with an AT LOCAL clause, these statements would return '08/06/01' for the current session time zone displacement, INTERVAL '01:00' HOUR TO MINUTE.

The following shows the results of the SELECT statements if the AT clause was not specified:

SET TIME ZONE INTERVAL '01:00' HOUR TO MINUTE;
SELECT CAST(TIMESTAMP '2008-05-31 22:30:00-08:00' AS DATE);

Result:

2008-05-31 22:30:00-08:00
-------------------------
                 08/06/01

SELECT TIMESTAMP '2008-06-01 06:30:00+00:00'
   AT TIME ZONE INTERVAL -'08:00' HOUR TO MINUTE;

Result:

2008-06-01 06:30:00+00:00 AT TIME ZONE INTERVAL -8:00 HOUR TO MINUTE
--------------------------------------------------------------------
                                           2008-05-31 22:30:00-08:00

SELECT TIMESTAMP '2008-06-01 06:30:00+00:00'
   AT TIME ZONE INTERVAL -'08:00' HOUR TO MINUTE (DATE);

Result:

2008-06-01 06:30:00+00:00 AT TIME ZONE INTERVAL -8:00 HOUR TO MINUTE
--------------------------------------------------------------------
                                                            08/06/01

SELECT TIMESTAMP '2008-06-01 06:30:00+00:00' (DATE);

Result:

2008-06-01 06:30:00+00:00
-------------------------
                 08/06/01

SELECT TIMESTAMP '2008-06-01 07:30:00' (DATE);

Result:

2008-06-01 07:30:00
-------------------
           08/06/01

The following shows the results of the SELECT statements if the AT clause was not specified, and the current session time zone displacement is INTERVAL -'08:00' HOUR TO MINUTE.

SET TIME ZONE INTERVAL -'08:00' HOUR TO MINUTE;
SELECT CAST(TIMESTAMP '2008-05-31 22:30:00-08:00' AS DATE);

Result:

2008-05-31 22:30:00-08:00
-------------------------
                 08/05/31

SELECT TIMESTAMP '2008-06-01 06:30:00+00:00'
   AT TIME ZONE INTERVAL -'08:00' HOUR TO MINUTE (DATE);

Result:

2008-06-01 06:30:00+00:00 AT TIME ZONE INTERVAL -8:00 HOUR TO MINUTE
--------------------------------------------------------------------
                                                            08/05/31

SELECT TIMESTAMP '2008-06-01 06:30:00+00:00' (DATE);

Result:

2008-06-01 06:30:00+00:00
-------------------------
                 08/05/31

SELECT CAST(TIMESTAMP '2008-06-01 07:30:00+01:00' 
   AS TIMESTAMP(0)) (DATE);

Result:

2008-06-01 07:30:00+01:00
-------------------------
                 08/05/31