<?php

/*
 * This file is part of the Dektrium project.
 *
 * (c) Dektrium project <http://github.com/dektrium/>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
 
use yii\db\Schema;
use yii\db\Migration;

class m151218_234654_add_new_field_to_profile extends Migration
{
    public function up()
    {
        $this->addColumn('{{%profile}}', 'timezone', Schema::TYPE_STRING . (255));
    }

    public function down()
    {
        $this->dropcolumn('{{%profile}}', 'timezone');
        return false;
    }

}

Create timezone on the profile table
Create timezone on the profile table