title: Calculate difference between two datetimes
body: <p>I am using PHP and MySQL, and want to calculate date time difference between two datetimes. I have a message table, in that table <code>createdate</code> is one field. I want to find out day and time difference from current date in the format <code>1 day 2 hours ago</code>. What is the best way to go about this?</p>