如何检测从PHP指定的日期过去3小时？

How to detect past 3 hours from the date assigned in php? I have my recent script i don't know if where did I go wrong in my script.

   $currentdate =  "2012-05-29 21:00:01";
   $dateassigned =  "2012-05-29 18:00:00";
   $startTime = mktime() - 3*3600; 
   $getdate = strtotime($date);
   if($getdate >= $startTime) { 
   //if get date already past with 3 hour this will show yes 
    echo "yes"; 
   } else { 
    echo "no"; 
   }

Any help for this problem? Thank you.

not sure if you want comparison up to the second but

date("now -3 hours");

should return the time
Tue, 29 May 2012 14:48:01 +000001
You can use strtotime() to do comparison or date_diff() for php >= 5.3

If I understand your mean this should work:

$now = date('Y-m-j H:i:s');
$last3Hour = strtotime ( '-3 hour' , strtotime ( $now ) ) ;
$specificDate = "2012-05-29 18:00:00";
if(strtotime($specificDate) >= $last3Hour) { 
    echo "yes"; 
} else { 
    echo "no"; 
}