zen_get_category_name($category_id, $fn_language_id)
该函数主要返回一个目录的名字，输入参数为目录的ID和语言ID，因为zen cart支持多语言，目录可能有多个语言版本。
主要查询了 categories_description 表。在includes/database_tables.php中定义：
define(‘TABLE_CATEGORIES_DESCRIPTION’, DB_PREFIX . ‘categories_description’);
*/
函数源代码：function zen_get_category_name($category_id, $fn_language_id) {
global $db;
$category_query = "select categories_name
from " . TABLE_CATEGORIES_DESCRIPTION . "
where categories_id = '" . $category_id . "'
and language_id = '" . $fn_language_id . "'";
$category = $db->Execute($category_query);
return $category->fields['categories_name'];
}