UNIX TIMESTAMP GMT stored in sqlite in Integer, convert to local time zone

Question

in my table in sqlite i have stored a date in timestamp in gmt time zone, in this way:

CREATE TABLE task (
id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,
date INTEGER,
    name TEXT
);

when i query the database i want retrieve the date with the local time so:

NSTimeInterval now = [[NSDate date] timeIntervalSince1970];

the now timestamp is of my local time zone, so for example if it's possible i want do this:

SELECT id,date,name FROM task WHERE converttolocal(date) = now;

i want know if exist a function in sqlite like for instance converttolocal to automatically convert the timestamp...

EDIT

i found this:

strftime('%s',date, 'unixepoch', 'localtime')

but if for instance the date gmt in the database is: 1375660800 that is:

 GMT: Mon, 05 Aug 2013 00:00:00 GMT

after the function strftime the result is: 1375668000 that correspond at my local time:

 (CEST) Mine time zone: 05 agosto 2013 04:00:00

but i want that the result of the strftime function give me this: 1375653600 that is:

Mine time zone: 05 agosto 2013 00:00:00 CEST

Why doesn't give me this result?

Answer 1

To convert from a Unix timestamp to SQLite's default date format, use the unixepoch modifier. To convert a time from UTC to local time, use the localtime modifier. To convert from SQLite's default date format to a Unix timestamp, use strftime with the %s format:

SELECT id,date,name FROM task WHERE strftime('%s', date, 'unixepoch', 'localtime') = ?

It might be easier to use SQLite's built-in method to get the current time, which already is in UTC:

SELECT id,date,name FROM task WHERE datetime('%s', date, 'unixepoch') = datetime('now')

However, if you have only dates, you want to ignore the time portion. In that case, use date instead of datetime:

SELECT id,date,name FROM task WHERE date('%s', date, 'unixepoch') = date('now')

Answer 2

SELECT id,date,name FROM task WHERE datetime('date', 'unixepoch', 'localtime') = datetime('now','unixepoch');

This will work. But the left hand side value will never match with the right hand side and you will never retrieve a value, because you are capturing timestamps, by the time you compare, the timestamp value would have changed.

so , SELECT id,date,name FROM task WHERE converttolocal(date) = now; will never be true .