To: cnliou@so-net.net.tw
Cc: "" <pgsql-interfaces@postgresql.org>
Subject: Re: Inserting timestamp values from windowz application 
In-reply-to: <1070386056.30928.cnliou@so-net.net.tw> 
References: <1070386056.30928.cnliou@so-net.net.tw>
Comments: In-reply-to "cnliou" <cnliou@so-net.net.tw>
	message dated "Wed, 03 Dec 2003 01:27:36 +0800"
Date: Tue, 02 Dec 2003 13:06:25 -0500
Message-ID: <22898.1070388385@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

"cnliou" <cnliou@so-net.net.tw> writes:
> After project1.exe connects to postgres via libpq.dll, the 
> query
> SHOW TIME ZONE
> returns "unknown", which is as expected. Then I do the 
> insert from project1.exe:
> INSERT INTO test VALUES (CAST('2003-1-1' AS TIMESTAMP));
> What weird is that this datetime value is saved to column c1 
> as 2002-12-31 16:00:00 UTC.

This means that your system default timezone is UTC+8.

The fact that SHOW TIME ZONE returns "unknown" does not mean that your
time zone setting is UTC.  It means that the standard C library
interface doesn't provide any way to find out the setting in string
form :-(.  SHOW TIME ZONE can tell you something useful if either
(1) you've done a SET TIME ZONE, or (2) the variable TZ is
defined in the postmaster's environment.  Otherwise it says "unknown"
... but the C library nonetheless will find a time zone setting from
someplace.

> I need a "manual" way to explicitly tell postgres the 
> client's time zone by sending from project1.exe the query  
> "SET TIME ZONE -5" or the like to postgres.

What's so hard about that?

			regards, tom lane