使用 Codeigniter 的复杂查询连接答案

【问题标题】：Complex query join using Codeigniter使用 Codeigniter 的复杂查询连接
【发布时间】：2019-01-18 18:22:59
【问题描述】：

我有一个查询在 phpmyadmin 中产生结果，但在 codeigniter 中没有。

$sql = "SELECT express_interests.*, 
       cl_to  .User_Name AS ToClient, 
       cl_from.User_Name AS FromClient,
       cl_from.Member_Id AS FromMid,
       cl_to.Member_Id AS ToMid

FROM express_interests  
    INNER JOIN users AS cl_to ON cl_to.User_Id = express_interests.To_Id
    INNER JOIN users AS cl_from ON cl_from.User_Id = express_interests.User_Id";

我想在 codeignitor 中使用相同的查询。这是我用过的

$this->db->select('express_interests.*, 
       cl_to  .User_Name AS ToClient, 
       cl_from.User_Name AS FromClient,
       cl_from.Member_Id AS FromMid,
       cl_to.Member_Id AS ToMid
');

$this->db->from('express_interests');


$this->db->join('users AS cl_to', 'cl_to.User_Id = express_interests.To_Id');
$this->db->join('users AS cl_from', 'cl_from.User_Id = express_interests.User_Id');

当我使用它时，它会说

“字段列表”中的未知列“cl_to .User_Name”

在 codeigniter 中使用上述查询的正确方法是什么。

【问题讨论】：

标签： php mysql codeigniter codeigniter-3 codeigniter-2

【解决方案1】：

$this->db->select('express_interests.*, 
       cl_to  .User_Name AS ToClient, 
       cl_from.User_Name AS FromClient,
       cl_from.Member_Id AS FromMid,
       cl_to.Member_Id AS ToMid
');

替换为

$this->db->select('express_interests.*, 
       cl_to.User_Name AS ToClient, 
       cl_from.User_Name AS FromClient,
       cl_from.Member_Id AS FromMid,
       cl_to.Member_Id AS ToMid
');

表别名和列名之间不需要的间距

【讨论】：

【解决方案2】：

替换

cl_to  .User_Name AS ToClient,

与

cl_to.User_Name AS ToClient,

也可以直接在codeigniter中运行sql语句

$sql = "SELECT express_interests.*, 
   cl_to.User_Name AS ToClient,
   cl_from.User_Name AS FromClient,
   cl_from.Member_Id AS FromMid,
   cl_to.Member_Id AS ToMid

FROM express_interests  
INNER JOIN users AS cl_to ON cl_to.User_Id = express_interests.To_Id
INNER JOIN users AS cl_from ON cl_from.User_Id = express_interests.User_Id"; 

$result=$this->db->query($sql);

print_r($result->result());

die;

【讨论】：