不要认为它是可行的开箱即用没有雄辩。
你可以走原始路线：

$results = DB:table('posts')
    ->leftJoin('comments', 'posts.id', '=', 'comments.post_id')
    ->select('posts.*', 'comments.*', 'comments.id as comments_id')
    ->get(); 

foreach($results as &$result) 
{ 
    $result['comment'] = [
        'id' => $result['comment_id'], 
        'comment' => $result['comment'], 
        'comment_author' => $result['comment_author']
    ]; 
    unset($result['comment_author'], $result['comment_id']);
}

由于你使用的是DB facade而不是Eloquent，并且不能使用内置的with()方法，所以你必须自己实现它：

$posts = DB::table('posts')->get()->toArray();
$comments = DB::table('comments')->get()->toArray();

foreach($posts as &$post)
{
    $post->comments = array_filter($comments, function($comment) use ($post) {
        return $comment->post_id === $post->id;
    });
}

return $posts;

如果你想摆脱post_id的评论条目，你可以这样做：

$posts = DB::table('posts')->get()->toArray();
$comments = DB::table('comments')->get()->toArray();

foreach($posts as &$post)
{
    $comments = array_filter($comments, function($comment) use ($post) {
        return $comment->post_id === $post->id;
    });

    $post->comments = array_map(function ($comment) {
        unset($comment->id);
        return $comment;
    }, $comments);
}

return $posts;

（我猜运行时将类似于with()，因为毕竟MySql不提供开箱即用的功能）。

这里有一些新的信息：

$data= $DB->select("select posts.*,comments from posts left join comments on posts.id = comments.post_id");

我不知道这是不是工作，但你可以试试

你可以试试这个

$data= $DB->select("select *,(select json_agg(datas) from (select * from comments where posts.id=comments.post_id) as datas) as comments from posts;");

但是您可能还需要对注解进行解码

$products = Category::with('product')->get(array('category.qty','category.product_id','category.net_unit_price as price'));

    foreach ($products as $p){
        $pl['name'] = $p->product->name;
        $pl['image'] = $p->product->image;
        unset($pl->product);
    }