title: Calculating the number of days between two dates
body: <p>I have a mySQL database.</p>
  
  <p>I need to count the number of days between two dates.</p>
  
  <p>My client is going to fill an input <code>hm_date</code> with January 1, 1979 via php form to create a new record.</p>
  
  <p>I need a field <code>total_days</code> to calculate the total number of days from <code>hm_date</code> to the present day. I need this field to always update itself with each passing day.</p>
  
  <p>How do I make <code>hm_date</code> to appear with total days and be always updated?</p>
  
  <p>I asume this can be achieved server-side?</p>
  
  <p>Should I use <code>strototime()</code> ?</p>