title: mysql+php to subtract two times and display the differrence
body: <p>i've to display the differences between a column(<strong>reg_time</strong>) in mysql and the present time so that the final output (after some php to display in minutes or seconds or hours or days)
  be:</p>
  
  <p>Registered : <strong>8 hours ago</strong>.</p>
  
  <p>is there any function to do that?
  thanks</p>