title: Query get specific value in opencart
body: <p>Im biggner in opencart my issue is I add field in product table called (model_choice) , in the product.tpl page in path (catalog/view/theme/default/template/product/product.tpl) I want to get the value of the row (model_choice) for the selected product I already get the product id with <code>$this-&gt;request-&gt;get['product_id']</code> I try to get the value of (model_choice) with</p>
  
  <pre><code>$sql = $this-&gt;db-&gt;query('SELECT model_choice 
                          FROM '.DB_PREFIX.'product 
                          WHERE product_id = ' . $this-&gt;request-&gt;get['product_id']);
  $id = $sql -&gt;model_choice;
  </code></pre>