Magento自定义管理网格页面中的默认多个排序列

i write a Magento grid extend Mage_Adminhtml_Block_Widget_Grid, for custom Manage Customers page. I need sort multiple columns by default, then i write _prepareCollection method:

    protected function _prepareCollection()
  {
    $collection = Mage::getResourceModel('customer/customer_collection')
    ->addNameToSelect()
    ->addAttributeToSelect('customer_type')
    ->addAttributeToSelect('email')
    ->addAttributeToSelect('created_at')
    ->addAttributeToSelect('group_id')     
    ->addAttributeToSelect('customer_status')     
    ->joinAttribute('billing_postcode', 'customer_address/postcode', 'default_billing', null, 'left')
    ->joinAttribute('billing_city', 'customer_address/city', 'default_billing', null, 'left')
    ->joinAttribute('billing_telephone', 'customer_address/telephone', 'default_billing', null, 'left')
    ->joinAttribute('billing_region', 'customer_address/region', 'default_billing', null, 'left')
    ->joinAttribute('billing_country_id', 'customer_address/country_id', 'default_billing', null, 'left')
            ->addAttributeToSort('customer_status', 'asc')
            ->addAttributeToSort('customer_type', 'asc');
    $this->setCollection($collection);

    return parent::_prepareCollection();
  }

Note that customer_status and customer_type are attributes. But it does not work. I need help, thanks.

You can use below code

$collection->setOrder(array('customer_status', 'customer_type'), asc);