zen_categories_lookup($categories_id, $what_field = ‘categories_name’, $language = ‘’)
该函数主要通过目录ID和字段名返回目录信息表中指定的字段的值。默认返回的语言类型为当前使用的语言类型。
它主要对 categories 表和 categories_description 表进行操作。使用之前首先对这两表的结构熟悉，这样才知道该获取什么字段。
主要查询了 categories ，categories_description表。在includes/database_tables.php中定义：
define(‘TABLE_CATEGORIES’, DB_PREFIX . ‘categories’);
define(‘TABLE_CATEGORIES_DESCRIPTION’, DB_PREFIX . ‘categories_description’);
函数源代码： function zen_categories_lookup($categories_id, $what_field = 'categories_name', $language = '') {
global $db;
if (empty($language)) $language = $_SESSION['languages_id'];
$category_lookup = $db->Execute("select " . $what_field . " as lookup_field
from " . TABLE_CATEGORIES . " c, " . TABLE_CATEGORIES_DESCRIPTION . " cd
where c.categories_id ='" . (int)$categories_id . "'
and c.categories_id = cd.categories_id
and cd.language_id = '" . (int)$language . "'");
$return_field = $category_lookup->fields['lookup_field'];
return $return_field;
}