title: stmt bind_result() doesn't bind all columns
body: <p>I've got a simple query that I'm trying to bind to three variables in a fetch loop. Unfortunately, it picks up the first two columns and leaves the 3rd as an empty string... I'm at a loss... any ideas?</p>
  
  <pre><code> $db = new mysqli("host.com", "username", "password", "db_name");
  
   $q = "SELECT user_id, meta_key, meta_value FROM wp_usermeta WHERE (meta_key='first_name' OR meta_key='last_name') AND meta_value != '';";
   $stmt = $db-&gt;prepare($q);
   $stmt-&gt;execute();
   $stmt-&gt;bind_result($col1,$col2,$col3);
   while ( $stmt-&gt;fetch() ) {
        echo $col1." - ".$col2." - ".$col3."&lt;br /&gt;";
        }
  </code></pre>
  
  <p>Output:</p>
  
  <pre><code> 2 - first_name - 
   2 - last_name - 
   5 - last_name - 
   5 - first_name - 
   6 - first_name - 
   6 - last_name - 
   8 - last_name - 
   8 - first_name - 
   9 - first_name - 
   9 - last_name - 
  </code></pre>