CODEWITHSUNDEEP
sqlasp-classic
Dennis
Dennis

Reputation: 728

Classic ASP - Server Time vs. Local Time

I have a Classic ASP application that I am working with date cut offs. My server resides in Central Time, but I am in Eastern time. What happens is my app thinks it is an hour earlier and my cut offs are an hour late. I am sure they would be 2 hours early if a user was in Pacific time.

What I am trying to figure out is if there is a way to either

  1. tell the server to show me local time when you do a GetDate() on SQL or Now() in ASP
  2. figure out some way to do an offset that I can run when the page first loads and use as needed.

I tried server side javascript, it returns Central Time too. Any help would be greatly appreciated!! Thanks in advance!

Dennis

UPDATE - 4/11/12 @ 1:12pm:

I think that I found a work around for my application, but it would not work generically. I have geographic data for the location I am working with - zip code. I can grab the timezone from that - it would not fully work right for users in other timezones looking at the location, but it does not matter for my app since I just need to be focused on the end time for that location.

This is the other other way(s) I found were provided by JohnB below (specifically #4). thanks everyone. http://www.webmasterworld.com/forum47/600.htm (bottom)

Upvotes: 2

Views: 11540

Answers (6)

Salih
Salih

Reputation: 17

You can check e.g. the website http://worldclockapi.com. You can take the current time as timezone.

Example: At http://worldclockapi.com/api/json/est/now. you can see EST current date, time and other data..

Example: At http://worldclockapi.com/api/json/pst/now you can see PST current date, time and other data...

And you can use XMLHTTP for getting data from external site.

private Function GETHTTP(adres)
     Set StrHTTP = Server.CreateObject("Microsoft.XMLHTTP" )
     StrHTTP.Open "GET" , adres, false
     StrHTTP.sEnd
     GETHTTP = StrHTTP.Responsetext
     Set StrHTTP = Nothing
End Function

full_data= GETHTTP("http://worldclockapi.com/api/json/est/now")

Afterwards, you use split to to separate by comma:

parts=split(full_data,",")
response.write parts(1)

Upvotes: 0

foxontherock
foxontherock

Reputation: 1842

New solution to an old question...

We just had this issue when moving a server from "eastern standard time" to "utc", with all our asp classic apps.
But, we're using SQL server 2017.

And, if you're using SQL server 2016+, you can use the new "at time zone" keyword.

Get your current "offset" from that query: 

select datediff(hour, GETUTCDATE() at time zone 'eastern standard time', GETUTCDATE()) as offset

Then, use that offset to handle all your dates in your ASP code, with functions like:

function fromUTC(dt)
    fromUTC = dateadd("h", tzOFFSET, dt)
end function

function toUTC(dt)
    toUTC = dateadd("h", -1 * tzOFFSET, dt)
end function

function getNow
    getNow = fromUTC(now)
end function

You can replace all "now" with "getNow" in your code.

Warning: that this offset is fixed according to the current date. If you need to handle dates from different daylight period, you can use the "at time zone" syntax directly in your SQL query, like: 

DECLARE @timezone NVARCHAR(100) = N'eastern standard time'
SELECT 
    u.name, 
    u.last_visit   at time zone @timezone as last_visit_tz,
    u.date_created at time zone @timezone as date_created_tz
FROM users u

Upvotes: 0

Matt Johnson-Pint
Matt Johnson-Pint

Reputation: 241525

In general, Time zone manipulation can't be done directly in classic ASP.

However, if you have full control of the server where the code is running, you can install a COM component written in a language that does have time zone support, then use that component from your classic ASP environment.

For example, you might write the following component in .NET with C#:

using System;
using System.Runtime.InteropServices;

namespace TimeZoneInfoCom
{
    [ComVisible(true)]
    [ClassInterface(ClassInterfaceType.AutoDispatch)]
    [Guid("E0C70A94-352D-4C0B-8C2E-8066C88565C5")]
    public class TimeZoneConverter
    {
        public DateTime NowInZone(string timeZoneId)
        {
            return TimeZoneInfo.ConvertTimeBySystemTimeZoneId(DateTime.UtcNow, timeZoneId);
        }

        public DateTime Convert(DateTime dateTime, string sourceZoneId, string targetZoneId)
        {
            TimeZoneInfo sourceTimeZone = TimeZoneInfo.FindSystemTimeZoneById(sourceZoneId);
            TimeZoneInfo targetTimeZone = TimeZoneInfo.FindSystemTimeZoneById(targetZoneId);
            return TimeZoneInfo.ConvertTime(dateTime, sourceTimeZone, targetTimeZone);
        }
    }
}

You would then compile this, copy the DLL to your server, and register it as a COM component (using RegAsm.exe).

Then you could call it in your Classic ASP page, like so:

<html>
<body>

Server Time: <%= Now() %><br>
<br>

<% 
Dim tzconverter
Set tzconverter = Server.CreateObject("TimeZoneInfoCom.TimeZoneConverter")
%>

US Pacific Time:  <%= tzconverter.NowInZone("Pacific Standard Time") %><br>
US Mountain Time:  <%= tzconverter.NowInZone("Mountain Standard Time") %><br>
US Central Time:  <%= tzconverter.NowInZone("Central Standard Time") %><br>
US Eastern Time:  <%= tzconverter.NowInZone("Eastern Standard Time") %><br>
UTC:  <%= tzconverter.NowInZone("UTC") %><br>

<br>

Conversion Example:
<%

Dim originalTime, convertedTime
originalTime = #12/31/2014 00:00:00#
convertedTime = tzconverter.Convert(originalTime, "UTC", "Tokyo Standard Time")
Response.Write(convertedTime)

%>

<%
' Don't forget to destroy the com object!
Set tzconverter = Nothing
%>

</body>
</html>

If you get an "ActiveX component can't create object" error, be sure that you have set "Enable 32-Bit Applications" to True in IIS, under the advanced settings for your application pool.

With regard to SQL Server - If you search, you may find a handful of posts showing ways you can manipulate time in SQL Server, through elaborate stored procedures that either have fixed offsets, fixed time zone rules, or rely on tables of time zone data. I usually advise against any of these approaches because they are too brittle.

  • Fixed offsets are bad because they don't account for daylight saving time.
  • Fixed rules are bad because time zone rules can (and do) change. Editing stored procs to keep up with these changes is too fragile (IMHO).
  • Maintaining tables of time zone data is a little better, but usually I find these tables to not be maintained well. If you go down this route, be sure to put a procedure in place for updating the tables periodically.

Upvotes: 1

JohnB
JohnB

Reputation: 18982

EDIT

I tried server side javascript, it returns Central Time too.

Did you mean to say client side JavaScript? You definitely need to use client side script to get the user's device time (not server side script).

You should read this:

Primer on dealing with multiple time zones:

1) Make sure your database server is set to the correct Date/Time in its time zone. Properly account for Daylight Savings Time in its location. Set the server to do this automatically.

2) Create a table in your database with time zones and their offset from UTC (GMT).

3) Always store Now() Date/Time in UTC. Every database vendor should have a UTC Date/Time Now() function (i.e. SYSUTCDATETIME() for SQL Server). This way all times are stored in a universal format agnostic to where the user happens to be sitting. Call Now() from your database, not the client, because mobile devices could be anywhere, but your database server stays in one spot.

4) Have user input their local time zone and store it in your database.

5) When displaying Date/Time stored in UTC back to the user, convert the UTC Date/Time back to the user's time zone using the user's time zone offset. SQL Server makes this a little easier with datetimeoffset.

6) If the user is setting an alarm, have them enter the trigger Date/Time in their local time zone. This way the user can change their local time zone if they move. Also, if time zone rules change you can just fix your time zone table (#2) and then the alarm will still trigger correctly. In your code, to test for alarm trigger, convert trigger time to UTC, and then compare against server time in UTC (i.e. SYSUTCDATETIME()).

7) Daylight Savings Time is tricky! (see 1st link)

Upvotes: 3

msigman
msigman

Reputation: 4524

Getting the users time zone

http://www.pageloom.com/automatic-timezone-detection-with-javascript

From what I understand about this JavaScript code it is very accurate and will be able to return the offset from UST, the corresponding Olson Database timezone name, and handle the daylight savings time issue (ex. -5:00, America/New_york, true).

The only hurdle you will face after getting this code working on your html page will likely be getting these values to asp and then to sql if that is what you need. I achieved this by sending these values as a $.post using JQuery. I think this is the easiest way to do it. I believe the other alternatives are using an AJAX command or cookies.

After I got the values from the JavaScript code to the server I stored them as session variables so they would change if the user on my site logged in from a different timezone then usual. However they could easily be saved to the database as well.

//replace this comment with the most updated timezonedetect code from that first link
var timezone = jstz.determine_timezone();
var tzoffset = timezone.offset();
var tzname = timezone.name();
var tzdst = timezone.dst();
$.post("tzdetect.asp", { tzoffset: tzoffset, tzname: tzname, tzdst: tzdst } );

Then you need to set up the receiving file tzdetect.asp on the server to store the time zone once it's sent.

Working with the time zone once you have it

This article has a good solution to your problem: http://www.codeproject.com/Articles/31146/SQL-2005-Time-Zone-Conversion-Functions

Approach is to set up a scalar function called NEW_TIME that takes three parameters:

  • date to convert
  • original time zone value
  • conversion time zone

and the function returns the converted value.

Upvotes: 0

Jatin
Jatin

Reputation: 1708

I think if you choose from below the one you need and then put at the top of your page it will default to that location instead of the server - http://msdn.microsoft.com/en-us/library/ms524330(v=vs.90).aspx

' This file does not need @LCID or @CODEPAGE and 
'  it does not need to be saved in UTF-8 format because  
'  there are no literal strings that need formatting or encoding. 

Response.Codepage = 65001 
Response.Charset = "utf-8" 

' See what happens when you uncomment the lines below. 
'Response.Codepage = 1252 
'Response.Charset = "windows-1252" 

ShowDateTimeCurrency 1033, "North America" 
ShowDateTimeCurrency 1041, "Japan" 
ShowDateTimeCurrency 1049, "Russia" 
ShowDateTimeCurrency 1031, "Germany" 
ShowDateTimeCurrency 1025, "Saudi Arabia" 
ShowDateTimeCurrency 1081, "India" 
ShowDateTimeCurrency 2052, "China" 
ShowDateTimeCurrency 1042, "Korea" 

Sub ShowDateTimeCurrency(iLCID, sLocale) 
  Response.LCID = iLCID 
  Response.Write "<B>" & sLocale & "</B><BR>" 
  Response.Write FormatDateTime(Date, 1) & "<BR>" 
  Response.Write FormatDateTime(Time, 3) & "<BR>" 
  Response.Write FormatCurrency(1000) & "<BR>" 
  Response.Write FormatNumber(50, 3, 0, 0, -1) & " & " & FormatNumber(.02, 3, 0, 0, -1) & "<BR><BR>" 
End Sub

Have a look here - http://msdn.microsoft.com/en-us/library/ms524330(v=vs.90).aspx

or another way would be to use date addadd function for time

Please Mark as answer if it helps thanks

Upvotes: -2

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