CodeIgniter子查询的问题

Question

$query=$this->db->query('SELECT g.gallery_id, g.gallery_title, (
          SELECT i.gallery_image_path 
          FROM nepal_gallery_image AS i 
          WHERE i.gallery_id = g.gallery_id 
          AND i.gallery_image_status = "Enabled" 
          LIMIT 0 , 1) AS gallery_image_path 
         FROM nepal_gallery AS g 
         WHERE g.gallery_status = "Enabled"'); 

上面的查询给出了正确的输出。

然而，当我使用CI子查询库：

$this->load->library('Subquery'); 
$this->db->select('g.gallery_id,g.gallery_title'); 
$sub = $this->subquery->start_subquery('select'); 
$sub ->select('i.gallery_image_path') 
    ->from('nepal_gallery_image AS i')     
    ->where(array('i.gallery_image_status'=>"Enabled", 
        'i.gallery_id'=>"g.gallery_id")) 
    ->limit(0,1); 
$this->subquery->end_subquery('gallery_image_path'); 
$this->db->from('nepal_gallery AS g'); 
$this->db->where('g.gallery_stats',"Enabled"); 
$query=$this->db->get(); 

结果查询是：

SELECT `g`.`gallery_id` , `g`.`gallery_title` , (
    SELECT `i`.`gallery_image_path` 
    FROM (`nepal_gallery_image` AS i) 
    WHERE `i`.`gallery_image_status` = 'Enabled' 
    AND `i`.`gallery_id` = 'g.gallery_id' 
    LIMIT 0 , 1) AS gallery_image_path 
FROM (`nepal_gallery` AS g) 
WHERE `g`.`gallery_status` = 'Enabled' 

，并没有如预期的输出。

在第一个查询输出

<table> 
    <tr> 
     <th> gallery_id</th> 
     <th> gallery_title</th> 
     <th> gallery_image_path </th> 
    </tr> 
    <tr> 
     <td>1</td> 
     <td>Gallery 1</td> 
     <td>images/image1.jpg</td> 
    </tr> 
    <tr> 
     <td>2</td> 
     <td>Gallery 2</td> 
     <td>images/image2.jpg</td> 
    </tr> 
    </table> 

然而，在后来的查询，输出是

<table> 
    <tr> 
     <th> gallery_id</th> 
     <th> gallery_title</th> 
     <th> gallery_image_path </th> 
    </tr> 
    <tr> 
     <td>1</td> 
     <td>Gallery 1</td> 
     <td>NULL</td> 
    </tr> 
    <tr> 
     <td>2</td> 
     <td>Gallery 2</td> 
     <td>NULL</td> 
    </tr> 
    </table> 

看来问题是子查询。

任何人都可以帮助我吗？

Answer 1

问题是子查询的条件是把你的表别名g作为字符串'g.gallery_id'避免CI保护字段的一种方法是通过在条件中传递第三个参数为false，因此CI不会尝试保护你的字段或表带反引号的名字。

试试这个

$sub ->select('i.gallery_image_path') 
->from('nepal_gallery_image AS i')     
->where(array('i.gallery_image_status'=>"Enabled", 
       'i.gallery_id'=>"g.gallery_id"), NULL, FALSE); 
              //--^^^^^^^^^^^^^^--here 
->limit(0,1); 

或简单的写你的条款manaully

$where = "i.gallery_id = g.gallery_id AND i.gallery_image_status = 'Enabled'"; 
    $sub ->select('i.gallery_image_path') 
->from('nepal_gallery_image AS i')     
->where($where,NULL,FALSE); 
->limit(0,1); 

Answer 2

->where(array('i.gallery_image_status'=>"Enabled", 
       'i.gallery_id'=>"g.gallery_id")) 

问题是与“i.gallery_id” =>“g.gallery_id” - CI正在建设的查询与“g.gallery_id”作为一个字符串...当它奥特是一个表列参考。如果您手动将“g.gallery_id”替换为“g”。“gallery_id”，它应该用作演示。

如果你不知道如何补救，请留下评论。 （这可能只是使用单引号的问题）。