用笨（活动记录）MySQL查询

Question

在笨我使用下面的查询使用：

$this->db->select('products.id, 
        categories.name as cat_name, 
        products.name as name, 
        products.product_image, 
        products.description, 
        products.price, 
        products.furl, 
        products.on_sale, 
        products.quantity_in_stock, 
        products.product_code, 
        products.rating_1, 
        products.rating_2, 
        products.rating_3, 
        products.rating_4, 
        products.rating_5, 
        products.rated_by, 
        products.discount, 
        ((products.rating_1+products.rating_2, 
        products.rating_3, 
        products.rating_4, 
        products.rating_5)/rated_by as calc) 
'); 

我得到一个错误检查近钙的SQL语法。请解释问题出在哪里以及为什么。 PS：我只是想by子句这样使用计算的依次是：

$this->db->order_by('calc','desc'); 
$this->db->get(); 

UPDATE：这是我所得到的，而执行这个查询：

Error Number: 1064 

你在你的SQL语法错误;检查对应于您的MySQL服务器版本的手册，以在'as calc'附近使用正确的语法FROM（products）JOIN categories ON categories。第1行的'ca'

Answer 1

如果您打算使用别名，那么您不希望CodeIgnioter会自动在列名称周围添加刻度线，因为这会导致错误。只是select()第二放慢参数设置为false关闭此行为：

$this->db->SELECT( 
       'products.id,categories.name as cat_name, 
        products.name as name, 
        products.product_image, 
        products.description, 
        products.price, 
        products.furl, 
        products.on_sale, 
        products.quantity_in_stock, 
        products.product_code, 
        products.rating_1, 
        products.rating_2, 
        products.rating_3, 
        products.rating_4, 
        products.rating_5, 
        products.rated_by, 
        products.discount, 
        ((products.rating_1+products.rating_2, 
        products.rating_3,products.rating_4, 
        products.rating_5)/rated_by as calc)', false) ; 

Answer 2

是的，你是正确的@约翰

$this->db->select('products.id,categories.name as cat_name, products.name as name,products.product_image,products.description,products.price,products.furl,products.on_sale,products.quantity_in_stock,products.product_code,products.rating_1,products.rating_2,products.rating_3,products.rating_4,products.rating_5,products.rated_by,products.discount,((products.rating_1+products.rating_2,products.rating_3,products.rating_4,products.rating_5)/rated_by as calc)', false) ; 

也为我工作