title: PHP mysql query is executing twice
body: <p>I have this PHP script:</p>
  
  <pre><code>$q = $dbc -&gt; prepare("
      UPDATE accounts 
      SET motivation = motivation-10 
      WHERE id = ?
  ");
  
  $q -&gt; execute(array($user['id']));
  </code></pre>
  
  <p>But it is subtracting 20 instead of ten. When I run the query in mysql it only subtracts ten.  Why?</p>