PHP UNIX TIME STAMP - php

Question

I have a date calendar in my php form which gives me date '19-05-2014'. I should compare this date to database time-modified (1400481271) exactly.
When converted '19-05-2014' to UNIX TIME STAMP, but I get the result as 1397858400 which was a wrong time stamp.
id userid timemodified
370 23 1400481271
329 24 1427771915
333 30 1428309816
332 32 1428303307
327 33 1427689703
328 34 1427710711
<?php
if ( preg_match('/^(?P<day>\d+)[-\/](?P<month>\d+)[-\/](?P<year>\d+)$/', '19-05-2014', $matches) )
{
$timestamp = mktime(0, 0, 0, ( $matches['month'] - 1 ), $matches['day'], $matches['year']);
echo $timestamp;
}
?>

Answer 1

The date you are trying to match is, converted to timestamp:
1400457600
If you got a different value you converted it wrong (maybe switched day and month or something similar).
It is, however, while close, still not identical to the given value 1400481271 in your database.
The reason for this becomes clear if you convert it back to a readable date:
05/19/2014 # 6:34am (UTC) 1400481271
For comparison, the given date:
05/19/2014 # 12:00am (UTC) 1400457600
As you can see there is a difference because it's the same date, but a different time.
The easiest way would be to retrieve only the date portion from the database.
You can do this in your SQL query like this:
SELECT DATE( FROM_UNIXTIME( timemodified ) ) AS modified
This will return 2014-05-19, which you can easily compare with your string.
Or, if you can even retrieve it in the same format you get it, so you don't need to rewrite your date with regex:
SELECT DATE_FORMAT( FROM_UNIXTIME( timemodified ), '%d-%m-%Y' ) AS modified
This will return 19-05-2014 for 1400481271.