Current DateTime is wrong using Strftime

Question

In my android application, I use STRFTIME function to get data from SQLite by comparing different Date Strings.

I set Promotion StartDate and EndDate to 2013-10-07 and 2013-12-31 respectively. Promotion exists when current DateTime is between StartDate and EndDate.

The following is a complete list of valid strftime() substitutions:

%d       day of month: 00
%f       fractional seconds: SS.SSS
%H       hour: 00-24
%j       day of year: 001-366
%J       Julian day number
%m       month: 01-12
%M       minute: 00-59
%s       seconds since 1970-01-01
%S       seconds: 00-59
%w       day of week 0-6 with Sunday==0
%W       week of year: 00-53
%Y       year: 0000-9999=

And I use the following query to retrieve the data.

Select * From Sal_Promotion p, Sal_Promotion_CustomerTypeAndProduct pd 
Where p.Sal_PromotionID = d.Sal_PromotionID and 
strftime('%s','now') >= strftime('%s',Sal_StartDate) and 
strftime('%s','now') = strftime('%s',Sal_EndDate) and 
Sal_CustomerTypeID = customerTypeID and 
p.Sal_PromotionID = promoID;

When I tested my application on 07 Oct 2013 morning 7 am, I get the following output.

Output:

StartDate: 2013-10-07 00:00:00 (Value: 1381104000)

EndDate: 2013-12-31 00:00:00 (Value: 1388448000)

CurrentDateTime: 2013-10-07 07:00:00 (Value: 1381100400)

CurrentDateTime value should be between StartDate and EndDate. But why the value is wrong? Current DateTime is 3600 seconds (1 hour) later than StartDate.

My current city is Singapore (GMT+8:00). Is it because of time zone difference?

Can someone point me out what is the problem?

Answer 1

The timezone offset is your problem. SQLite3 date and time functions default to UTC.

One solution is to just compare the date strings directly

date('now') >= Sal_StartDate and date('now) <= Sal_EndDate

You can also pass a 'localtime' option to the SQLite3 date and time functions. See the SQLite3 date and time functions documentation.