[英]How to JOIN three tables in Codeigniter
我正在使用 codeigniter 框架来开发一个音乐 cms。 我在 mysql 数据库中有 3 个表,目前我在“相册”表和“模型、控制器”中工作。 我想选择“专辑”表 1 并加入“专辑”->“cat_id”与“类别”->“cat_id”,并获取所有类别记录。
然后我想在“原声带”上加入“专辑”->“album_id”->“album_id”,然后从 A 到 Z 获取所有原声带记录。
请有人帮我展示正确的 codeigniter 查询,我如何选择和加入表然后从 3 个表中获取记录,?
表 1 -> 类别
cat_id
猫名
日期
表 2 -> 专辑
专辑编号
专辑名称
专辑详情
表 3 -> 原声带
专辑编号
track_title
在模型中使用此代码
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;
}
}
尝试这个
在你的模型中
如果你想获得所有专辑数据使用
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 $query->result ();
}
如果你想获得特定的专辑数据使用
function get_album_data($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 ();
}
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 $query->result ();
}
而对于数据试试这个......
function get_album_datum($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();
}7
855788
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 $query->result_array();
}
尝试如下:
public function funcname($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();
return $query->result_array();
}
如果没有找到结果 CI 返回 false 否则为 true
public function getdata(){
$this->db->select('c.country_name as country, s.state_name as state, ct.city_name as city, t.id as id');
$this->db->from('tblmaster t');
$this->db->join('country c', 't.country=c.country_id');
$this->db->join('state s', 't.state=s.state_id');
$this->db->join('city ct', 't.city=ct.city_id');
$this->db->order_by('t.id','desc');
$query = $this->db->get();
return $query->result();
}
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