title: Stack value of my row instead of having multiple
body: <p>So I've got a table that looks like this:</p>
  
  <pre><code>username - item - amount
  user1 - sword - 1
  user1 - sword - 1
  user1 - sword - 1
  user2 - sword - 1
  user2 - sword - 1
  </code></pre>
  
  <p>How do I make it so that when I add an item to one of the users, they stack like this instead:</p>
  
  <pre><code>username - item - amount
  user1 - sword - 3
  user2 - sword - 2
  </code></pre>
  
  <p>the code for adding item:</p>
  
  <pre><code>$sql = "insert into items (username, item, amount) values ('".$_SESSION['user_name']."', 'sword', '1')";
  </code></pre>