console/migrations/m160216_180149_tean_date_change.php

<?php

use yii\db\Migration;

class m160216_180149_tean_date_change extends Migration
{
    public function up()
    {
        $this->dropColumn('team', 'experience_from');
        $this->addColumn('team', 'experience_from', $this->integer());
    }

    public function down()
    {
        $this->dropColumn('team', 'experience_from');
        $this->addColumn('team', 'experience_from', $this->timestamp());
    }
}