title: DATEDIFF() Parameter Issue
body: <p>The old DATEDIFF() allowed users to use 3 parameters, and I was trying to do this so I could get hours out of my DATEDIFF rather than days, (I'm trying to show hours since a post). In my database I'm using a TIMESTAMP and this line of code to pull a value, and obviously it doesn't work because I have the extra parameter. Once I remove the 'hour' or 'hh' the query runs and returns a value in days.</p>
  
  <p><CODE>SELECT DATEDIFF(hour, CURDATE(), (SELECT Post_Date FROM Post_T WHERE pk_PostID = 1) )</CODE></p>
  
  <p>Is there an easy way I can return the hourly value? </p>
  
  <p>Also I'm using MYSQL Version 5.5.20.</p>