合并和排序两个 Eloquent 集合?

I've two Collections and I want merge it to one variable (of course, with ordering by one collumn - created_at). How Can I do that?

我的控制器看起来像:

$replies = Ticket::with('replies', 'replies.user')->find($id);
$logs = DB::table('logs_ticket')
        ->join('users', 'users.id', '=', 'mod_id')
        ->where('ticket_id', '=', $id)
        ->select('users.username', 'logs_ticket.created_at', 'action')
        ->get();

我的输出查找例如:

回复:

ID | ticket_id | username | message | created_at
1  | 1         | somebody | asdfghj | 2014-04-12 12:12:12
2  | 1         | somebody | qwertyi | 2014-04-14 12:11:10

日志:

ID | ticket_id | username | action | created_at
1  | 1         | somebody | close  | 2014-04-13 12:12:14
2  | 1         | somebody |  open  | 2014-04-14 14:15:10

我想要这样的东西:

ticket_id | table | username | message | created_at
1         |replies| somebody | asdfghj | 2014-04-12 12:12:12
1         | logs  | somebody |  close  | 2014-04-13 12:12:14
1         | logs  | somebody |  open   | 2014-04-14 11:15:10
1         |replies| somebody | qwertyi | 2014-04-14 12:11:10

我的票证模型看起来是这样的:

<?php

class Ticket extends Eloquent {

    protected $table = 'tickets';

    public function replies() {
        return $this->hasMany('TicketReply')->orderBy('ticketreplies.created_at', 'desc');
    }

    public function user()
    {
        return $this->belongsTo('User');
    }
}
?>

SELECT * FROM
(
    SELECT
        `r`.`ticket_id`,
        'replies' AS `table`,
        `u`.`username`,
        `r`.`message`,
        `r`.`created_at`
    FROM `replies` AS `r`
    LEFT JOIN `users` AS `u`
        ON `r`.`user_id` = `u`.`id`
    WHERE `r`.`ticket_id` = ?
) UNION (
    SELECT
        `l`.`ticket_id`,
        'logs' AS `table`,
        `u`.`username`,
        `l`.`action` AS `message`,
        `l`.`created_at`
    FROM `logs` AS `l`
    LEFT JOIN `users` AS `u`
        ON `l`.`user_id` = `u`.`id`
    WHERE `l`.ticket_id` = ?
)
ORDER BY `created_at` DESC