带codeigniter的MySQL查询（活动记录）

Question

我在codeigniter中使用以下查询：

$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)
');

我得到一个错误来检查calc附近的sql语法。 请解释问题的位置和原因。 ps：我只是想按照这样的顺序使用calc：

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

更新：这是我执行此查询时得到的：

Error Number: 1064

您的SQL语法有错误; 检查与您的MySQL服务器版本对应的手册，以便在'as calc）附近使用正确的语法FROM（ products ）JOIN categories ON categories 。 第1行的id = products .`ca'

Answer 1

如果您打算使用别名，那么您不希望CodeIgnioter自动在列名周围添加刻度，因为它会破坏。 只需将select()的第二个参数设置为false即可关闭此行为：

$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，你是对的@John

$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