Db::table('article as a')
    ->leftJoin('comment as b', 'a.id', '=', 'b.article_id')
    ->offset(0)
    ->limit(100)
    ->get()
    ->toArray();
然后通过php循环处理结果集

\app\model\Article::with(['comment' => function ($query) use () {
    }])->get()
        ->map(function ($query) {
            $query->setRelation('comment', $query->comment->take(3));
            return $query;
        })
        ->toArray();
上述直接一次性查出