Check elapsed time in PHP from a MySQL datetime - php

How can I check how many seconds past the current time to a time in my MySQL database?
Example: The current time right now is 2018-07-21 10:04:20, and the time in my database is 2018-07-20 21:58:40.
I want to get how many seconds past the datetime in my database to the current date time.

You can use the strtotime() to convert your Date-Time to Unixtime an time() to get actual Timestamp:
$timestamp = strtotime("2018-07-21 10:04:20"); //replace with your DB-date
$diff = time() - $timestamp ; //calculate the Difference
echo $diff; //negative number is in the future

Just turn the date into number using strtotime.
$seconds = abs(strtotime($currentDate) - strtotime($dbDate));
I put abs in case of the result is negative.
strtotime returns the difference in seconds between 01-01-1970 and the date in parameter.

Related

PHP date() is wrong when using a UTC timestamp

$dayBasedOnUTC = date('l', $_GET['day']);
Why is it that when I echo the value of $dayBasedOnUTC the day returned is a Tuesday?
The UTC value of $_GET['day'] is: 1409393126144
If you put that number into any Unix Timestamp Converter you will see the date is Saturday.
It appears that 1409393126144 is a Javascript timestamp, which is counted in milliseconds. PHP expects its UNIX timestamps in seconds though. So 1409393126144 to PHP is a timestamp in the far future.
Divide by 1000 to get the correct value:
echo date('l', 1409393126144 / 1000);

PHP calculating time difference, result 1 hour wrong

I want to calculate difference of two times and print it in pretty way. I know the difference will never exceed 24 hours, so I tried the following
$time = 7200; //time difference in seconds
date("H:i:s", $time); // should print 02:00
The result is unexpected, it prints 03:00 instead.
What am I doing wrong?
Why not the DateTime::diff??
Here, check PHP.net for DateTime class
Grabbed from php.net datetime diff page:
$datetime1 = new DateTime('2009-10-11');
$datetime2 = new DateTime('2009-10-13');
$interval = $datetime1->diff($datetime2);
echo $interval->format('%R%a days');
//Outputs +2 days
The PHP date() function is meant for formatting absolute time stamps (as in "Friday, 20 July 2012, 15:02 UTC"), not for time differences (as in "3 hours and 5 minutes ago").
In some cases, it is possible to trick date() into producing something that looks like a correctly formatted time difference by setting your time zone to UTC and relying on the fact that the Unix epoch happens to fall on midnight in UTC. However, even then, this will only work for positive time differences of less than 24 hours.
Instead, the correct solution is to use a function designed for formatting time differences, or write one yourself. Here's a simple function to do so:
function format_time_difference ( $delta ) {
$sign = ( $delta < 0 ? "-" : "" );
$delta = abs( $delta );
return sprintf( "%s%02d:%02d:%02d", $sign, $delta / 3600,
($delta / 60) % 60, $delta % 60 );
}
Of course, you can extend this function to e.g. include days in the output if you like.
You should never use date to compute time difference. Firstly it is ugly hack. It was not intended for that purpose. And secondly, it works reliably only when timezone set to UTC.
Now, why it does not work:
PHP function date takes two arguments, format and timestamp, the latter is defined as number of seconds from 1st January 1970 00:00 UTC called unix epoch. So if you call date("H:i", 3600) and your timezone is set to UTC, it will return "01:00", cause it represents time one hour after unix epoch and the epoch was at the midnight.
The problem is, unix epoch was at the midnight only in UTC, not in the other timezones. And this is the source of the incorrect result.

How To Change A Unix Timestamp In The Future To Seconds Remaining

I am trying to create a javascript countdown timer;
I have a string that is in the format of YYYY-MM-DD HH:MM:SS .
This could be any time up to 6 months in the future.
What would be the best way to go about getting the time remaining in seconds from now until the future time. This could be implemented in PHP.
Thanks in advance!
In PHP you can use strtotime, which takes a string representation of a date and returns the unix timestamp.
Then use microtime to get the current unix timestamp, and find the difference. This will be the number of milliseconds remaining, so divide it by 1000 to get it in seconds.
http://php.net/manual/en/function.strtotime.php
http://php.net/manual/en/function.microtime.php
This should work:
$currentTime = explode(" ", microtime());
$currentTime = $currentTime[1];
$futureTime = strtotime("YYYY-MM-DD HH:MM:SS"); // insert your date here
$timeRemaining = ($futureTime - $currentTime) / 1000;
How are you getting this string-based timestamp? A unix timestamp is actually already "number of seconds since 1970-01-01 00:00:00". That looks like a native MySQL date string.
If it is coming out of MySQL, you can convert it to a unix-style timestamp with UNIX_TIMESTAMP(), e.g.
SELECT unix_timestamp(datetimefield) ...
and then convert it to a Javascript timestamp by multiplying by 1000 (JS timestamps have the same epoch, but in milliseconds).
If you're stuck in PHP, you can go quick/dirt with
$timestamp = strtotime($time_string);
$js_timestamp = $timestamp * 1000;

Compare timestamp to date

I need to compare a timestamp to a date. I would just like to compare the date portion without the time bit. I need to check whether a timestamp occurs on the day before yesterday i.e. today - 2.
Could you show me a snippet please? Thank you.
I've been reading through the PHP docs but couldn't find a very clean way of doing this. What I found was converting the timestamp to a date with a particular format and comparing it to a date which I get by doing a time delta to get the date before yesterday and converting it to a particular format. Messy.
You can arcieve this by using the function strtotime.
To round to a day I personaly like to edit the timestamp. This is a notations of seconds since epoch. One day is 86400 seconds, so if you do the following caculation:
$time = $time - ( $time % 86400 );
You can convert it back to a date again with the date function of PHP, for example:
$readableFormat = date( 'd-m-Y', $time );
There is also much on the internet about this topic.
you can use the strtotime function
<?php
$time = strtotime("5 june 2010");
$before = strtotime("-1 day",$time);
$after = strtotime("+1 day",$time);

how to subtract two dates and times to get difference

i have to sent an email when a user register email contain a link that is become invalid after six hours
what i m doing when email is sent i update the db with field emailSentDate of type "datetime"
now i got the curent date and time and has made to the same formate as it is in db now i want to find that both these dates and time have differenc of 6 hours or not so that i can make link invalid but i donot know how to do this
my code is look like this i m using hardcoded value for db just for example
$current_date_time=date("Y-m-d h:i:s");
$current=explode(" ",$current_date_time);
$current_date=$current[0];
$current_time=$current[1];
$db_date_time="2010-07-30 13:11:50";
$db=explode(" ",$db_date_time);
$db_date=$db[0];
$db_time=$db[1];
i do not know how to proceed plz help
<?php
//$now = new DateTime(); // current date/time
$now = new DateTime("2010-07-28 01:11:50");
$ref = new DateTime("2010-07-30 05:56:40");
$diff = $now->diff($ref);
printf('%d days, %d hours, %d minutes', $diff->d, $diff->h, $diff->i);
prints 2 days, 4 hours, 44 minutes
see http://docs.php.net/datetime.diff
edit: But you could also shift the problem more to the database side, e.g. by storing the expiration date/time in the table and then do a query like
... WHERE key='7gedufgweufg' AND expires<Now()
Many rdbms have reasonable/good support for date/time arithmetic.
What you can do is convert both of your dates to Unix epoch times, that is, the equivalent number of seconds since midnight on the 31st of December 1969. From that you can easily deduce the amount of time elapsed between the two dates. To do this you can either use mktime() or strtotime()
All the best.
$hoursDiff = ( time() - strtotime("2010-07-30 13:11:50") )/(60 * 60);
I'd rather work with a timestamp: Save the value which is returned by "time()" as "savedTime" to your database (that's a timestamp in seconds). Subtract that number from "time()" when you check for your six hours.
if ((time() - savedTime) > 6 * 3600)
// more than 6h ago
or
"SELECT FROM table WHERE savedTime < " . (time() - 6 * 3600)
This might be the solution to your problem -> How to calculate the difference between two dates using PHP?

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