左连接在Laravel中获得一行

Question

我没有成功尝试leftjoin并获得所需的数据

这是我的代码:

$album  =   Albums::->where('users_id',$user_id)
                    ->leftJoin('photos',function($query){
                            $query->on('photos.albums_id','=','albums.id');
                            $query->where('photos.status','=',1);

                            // $query->limit(1);
                            // $query->min('photos.created_at');
                    })
        ->where('albums.status',1)->get();

评论是我的几个尝试......

我想从照片表中只获得一张与album_id首先更新的外键相关的记录,并且状态为1

请帮忙......

Answer 1

我用DB::raw()它来实现这一目标

$album  =   Albums::select( 'albums.*',
            DB::raw('(select photo from photos where albums_id  =   albums.id  and status = 1 order by id asc limit 1) as photo')  )
            ->where('users_id',$user_id)
            ->where('albums.status',1)->get();

@JarekTkaczyk的编码类似,并显示了我所需的相同结果,所以特别感谢他的时间和精力......

但是将quires我留下的执行时间与我的上述片段进行比较

select `albums`.*, (select photo from photos where albums_id    =   albums.id  and status = 1 order by id asc limit 1) as photo from `albums` where `users_id` = '1' and `albums`.`status` = '1'

拿 520?s - 580?s

和@JarekTkaczyk的

select `albums`.*, `p`.`photo` from `albums` left join `photos` as `p` on `p`.`albums_id` = `albums`.`id` and `p`.`created_at` = (select min(created_at) from photos where albums_id = p.albums_id) and `p`.`status` = '1' where `users_id` = '1' and `albums`.`status` = '1' group by `albums`.`id`

拿了 640?s - 750?s但两者也一样...

Answer 2

您可以使用它实现任意leftJoin或rightJoin(但后者将返回Photo的车型,所以可能你不会需要一个):

Albums::where('users_id', $user_id)
 ->leftJoin('photos as p', function ($q) {
   $q->on('photos.albums_id', '=', 'albums.id')
     ->on('photos.updated_at', '=', 
       DB::raw('(select min(updated_at) from photos where albums_id = p.albums_id)'))
     ->where('photos.status', '=', 1);
 })
 ->where('albums.status', 1)
 ->groupBy('albums.id')
 ->select('albums.*', fields from photos table that you need )
 ->get();