gistfile1.php

<?
class Customer extends \yii\db\ActiveRecord
{
    public function getOrders()
    {
        return $this->hasMany('Order', array('customer_id' => 'id'));
    }
}

class Order extends \yii\db\ActiveRecord
{
    public function getCustomer()
    {
        return $this->hasOne('Customer', array('id' => 'customer_id'));
    }
}