title: Do I need to set a foreign key for table row increments on mysql
body: <p>That title is way wrong, I couldn't think of a better sentence.</p>
  
  <p>I'm creating a PHP/MySQL bases forum where I want to display how many topics are in a particular forum. So far so good, my question is: how do I make the row for topic count increment each time I add a new topic under a forum and decrement when I delete a topic.</p>
  
  <p>I could make this happen in the script but maybe there's a better way to do this from the database?</p>
  
  <p>Thanks in anticipation :)</p>