如何在Codeigniter中加入三张表

Question

我正在使用codeigniter框架开发一个音乐cms。我有3个表在MySQL数据库中，目前我在“相册”表和“模型，控制器”工作。我想选择“专辑”表1并加入“类别” - >“cat_id”的“相册” - >“cat_id”，并获取所有类别记录。

然后我想加入“相册” - >“album_id”的“原声” - >“album_id”然后获取所有配乐记录A到Z

请别人帮我出示适当笨查询，如何我可以选择和JOIN表，然后从3个表中获取记录，？

表1 - >分类

• CAT_ID

• cat_name

• cat_title

• 日期

  表2 - >相册

• CAT_ID

• album_id

• ALBUM_TITLE

• album_details

  表3 - >原声

• album_id

• TRACK_TITLE

• track_url
• 日期

Answer 1

使用此代码模型

public function funcname($id) 
{ 
    $this->db->select('*'); 
    $this->db->from('Album a'); 
    $this->db->join('Category b', 'b.cat_id=a.cat_id', 'left'); 
    $this->db->join('Soundtrack c', 'c.album_id=a.album_id', 'left'); 
    $this->db->where('c.album_id',$id); 
    $this->db->order_by('c.track_title','asc');   
    $query = $this->db->get(); 
    if($query->num_rows() != 0) 
    { 
     return $query->result_array(); 
    } 
    else 
    { 
     return false; 
    } 
} 

Answer 2

试试这个

在模型中

如果妳想要得到的所有专辑数据使用

function get_all_album_data() { 

    $this->db->select ('*'); 
    $this->db->from ('Album'); 
    $this->db->join ('Category', 'Category.cat_id = Album.cat_id' , 'left'); 
    $this->db->join ('Soundtrack', 'Soundtrack.album_id = Album.album_id' , 'left'); 
    $query = $this->db->get(); 
    return $query->result(); 
} 

如果u想要得到具体的唱片数据使用

function get_album_data($album_id) { 

    $this->db->select ('*'); 
    $this->db->from ('Album'); 
    $this->db->join ('Category', 'Category.cat_id = Album.cat_id' , 'left'); 
    $this->db->join ('Soundtrack', 'Soundtrack.album_id = Album.album_id' , 'left'); 
    $this->db->where ('Album.album_id', $album_id); 
    $query = $this->db->get(); 
    return $query->result(); 
} 

Answer 3

试试这个数据...

function get_album_data() { 
    $this->db->select ('album.*,cat.*,s_track.*') 
     ->from ('albums as album'); 
     ->join ('categories cat', 'cat.cat_id = album.cat_id') 
     ->join ('soundtracks s_tracks ', 's_tracks.album_id = album.album_id'); 
    $query = $this->db->get(); 
    return $query->result(); 
} 

而基准试试这个...

function get_album_datum($album_id) { 
    $this->db->select ('album.*,cat.*,s_track.*') 
     ->from ('albums as album'); 
     ->join ('categories cat', 'cat.cat_id = album.cat_id') 
     ->join ('soundtracks s_tracks ', 's_tracks.album_id = album.album_id'); 
    $this->db->where ('album.album_id', $album_id); 
    $query = $this->db->get(); 
    return $query->row(); 
} 

Answer 4

Check bellow code it`s working fine and common model function also 
    supported more then one join and also supported multiple where condition 
order by ,limit.it`s EASY TO USE and REMOVE CODE REDUNDANCY. 

    ================================================================ 
    *Album.php 
    //put bellow code in your controller 
    ================================================================= 

    $album_id='';//album id 

    //pass join table value in bellow format 
    $join_str[0]['table'] = 'Category'; 
    $join_str[0]['join_table_id'] = 'Category.cat_id'; 
    $join_str[0]['from_table_id'] = 'Album.cat_id'; 
    $join_str[0]['join_type'] = 'left'; 

    $join_str[1]['table'] = 'Soundtrack'; 
    $join_str[1]['join_table_id'] = 'Soundtrack.album_id'; 
    $join_str[1]['from_table_id'] = 'Album.album_id'; 
    $join_str[1]['join_type'] = 'left'; 


    $selected = "Album.*,Category.cat_name,Category.cat_title,Soundtrack.track_title,Soundtrack.track_url"; 

    $albumData= $this->common->select_data_by_condition('Album', array('Soundtrack.album_id' => $album_id), $selected, '', '', '', '', $join_str); 
           //call common model function 

    if (!empty($albumData)) { 
     print_r($albumData); // print album data 
    } 

========================================================================= 
    Common.php 
    //put bellow code in your common model file 
======================================================================== 

    function select_data_by_condition($tablename, $condition_array = array(), $data = '*', $sortby = '', $orderby = '', $limit = '', $offset = '', $join_str = array()) { 
    $this->db->select($data); 
    //if join_str array is not empty then implement the join query 
    if (!empty($join_str)) { 
     foreach ($join_str as $join) { 
      if ($join['join_type'] == '') { 
       $this->db->join($join['table'], $join['join_table_id'] . '=' . $join['from_table_id']); 
      } else { 
       $this->db->join($join['table'], $join['join_table_id'] . '=' . $join['from_table_id'], $join['join_type']); 
      } 
     } 
    } 

    //condition array pass to where condition 
    $this->db->where($condition_array); 


    //Setting Limit for Paging 
    if ($limit != '' && $offset == 0) { 
     $this->db->limit($limit); 
    } else if ($limit != '' && $offset != 0) { 
     $this->db->limit($limit, $offset); 
    } 
    //order by query 
    if ($sortby != '' && $orderby != '') { 
     $this->db->order_by($sortby, $orderby); 
    } 

    $query = $this->db->get($tablename); 
    //if limit is empty then returns total count 
    if ($limit == '') { 
     $query->num_rows(); 
    } 
    //if limit is not empty then return result array 
    return $query->result_array(); 
}