FRONTEND_MVC/models/base/CommentsPull.php

<?php

namespace app\models\base;

use yii\db\ActiveRecord;

class CommentsPull extends ActiveRecord
{
    public static function getDb()
    {
        return \Yii::$app->old_db;
    }

    public static function tableName()
    {
        return "{{%comment_pulls}}";
    }

}