计算如果使用PHP小于或等于24小时

I want to calculate the times between two set times (Cron job run 1 Hour, every Hour).

E.G:

2:18 PM on 20/06/2012 3:00 PM on 21/06/2012 * Cron Job Runs, More than 24 Hours

How would I calculate this in PHP to do a task that I will develop later.

Script I've attempted:

define("SECONDS_PER_HOUR", 60*60);
date_default_timezone_set('UTC');

$result = mysql_query("SELECT * FROM tickets") or die(mysql_error());

while($row = mysql_fetch_array($result)) {
    // Calculate the start time
    $str = $row['openTime'] . " " . $row['openDate'];

    $startdatetime = strtotime($str);

    $enddatetime = time();

    // calculate the difference in seconds.

    $difference =  $enddatetime - $startdatetime;

    $hoursDiff = $difference / SECONDS_PER_HOUR;

    $minutesDiffRemainder = $difference % SECONDS_PER_HOUR;

    echo $row['ticketID'] . ": " . $hoursDiff . "h " . $minutesDiffRemainder . "m<br />";
}

Have you considered actually doing a query that does what you need and not pull all data and doing the comparison in PHP? You could do

SELECT * from TICKETS WHERE DATE_ADD(open time, INTERVAL 24 HOUR) > CURTIME();

From reading your code, I'd assume you need to make the opentime field is a timestamp, containing both date and time. But that is the sensible choice in most cases, anyway.