add button inside custom column in sales order grid page

Question

I added new column in Sales Order Grid & successfully added title [say download] of column, now i want to add button [ say button name download1] for all rows of that column.

I did't created any column in database as i dont want to fetch anyy value from database.

app/code/community/Raveinfosys/Deleteorder/Block/Adminhtml/Sales/Order/Grid.php : Function : _prepareColumns()

$this->addColumn('download',
            array(
                'header'=> Mage::helper('sales')->__('download'),
                'width' => '70px',
                'index' => 'download1',  
                'type' => 'text'         
            ));

Answer 1

Try with render method

**''renderer'  => 'module/adminhtml_sales_order_render_delete',',**

Answer 2

To extend Magento 2 answer , i added as below :

app/code/community/Raveinfosys/Deleteorder/Block/Adminhtml/Sales/Order/Grid.php : Function : _prepareColumns()

if (Mage::getSingleton('admin/session')->isAllowed('sales/order/actions/view')) {
            $this->addColumn('action',
                array(
                    'header'    => Mage::helper('sales')->__('Action'),
                    'width'     => '100px',
                    'type'      => 'action',
                    'getter'     => 'getId',
                    'renderer'  => 'deleteorder/adminhtml_sales_order_render_delete',
                    'filter'    => false,
                    'sortable'  => false,
                    'index'     => 'stores',
                    'is_system' => true,
            ));
        }

app/code/community/Raveinfosys/Deleteorder/Block/Adminhtml/Sales/Order/Render - Delete.php :

class Raveinfosys_Deleteorder_Block_Adminhtml_Sales_Order_Render_Delete extends Mage_Adminhtml_Block_Widget_Grid_Column_Renderer_Abstract
{
    public function render(Varien_Object $row)
    {
        $getData = $row->getData();
        $message = Mage::helper('sales')->__('Are you sure you want to delete this order?');
        $orderID = $getData['entity_id'];
        $view = $this->getUrl('*/sales_order/view',array('order_id' => $orderID));
        $delete = $this->getUrl('*/deleteorder/delete',array('order_id' => $orderID));
        $link = '<a href="'.$download.'">Download</a>&nbsp;&nbsp;&nbsp;&nbsp;<a>';
        return $link;
    }
}