title: MySQL - How to SUM times?
body: <p>I have a table that contains date-time values in this format:</p>
  
  <p><strong>START</strong>                   </p>
  
  <p>1/13/2009   7:00:00AM       </p>
  
  <p><strong>END</strong></p>
  
  <p>1/13/2008   2:57:00PM</p>
  
  <p>I use the 'str to date' function to convert these into a date-time format.</p>
  
  <p>How do I calculate a difference between them?
  And then sum it all up so that it displays in total hours (ie total hours for week is 40:53).</p>
  
  <p>I was trying the timediff function but the results don't sum.</p>