数据库（子查询）

where parent_id=0

select shop_price from`kangarooisland_database`.`ki_goods`where cat_id in( select cat_id from`kangarooisland_database`.`ki_category` where parent_id=0) and is_hot=1 order by goods_id desc LIMIT 4

//查询数据库得到热销商品的价格 shop_price
$hot_goods_list = 'select shop_price from'. $GLOBALS['ecs']->table('goods') .'where cat_id in( select cat_id from'
    . $GLOBALS['ecs']->table('category') .' where parent_id='.$row['cat_id'].') and is_hot=1 order by goods_id desc LIMIT 4';