Get All Products Of An Order

$order = Mage::getModel(’sales/order’)->load($order_id);
$items = $order->getAllItems();
$itemcount=count($items);
$name=array();
$unitPrice=array();
$sku=array();
$ids=array();
$qty=array();
foreach ($items as $itemId => $item)
{
$name[] = $item->getName();
$unitPrice[]=$item->getPrice();
$sku[]=$item->getSku();
$ids[]=$item->getProductId();
$qty[]=$item->getQtyToInvoice();
}

Custom Account/Registration Fields

http://www.magentocommerce.com/wiki/custom_account/registration_fields

How to get currency symbol?

Here’s another way that might work for you:
Mage::app()->getLocale()->currency(Mage::app()->getStore()->
getCurrentCurrencyCode())->getSymbol()

or if you want to pass a certain currency code simply specify it:

Mage::app()->getLocale()->currency(’EUR’)->getSymbol()

How to add new db field where you can store values seperated by commas?

It took me some time to find out that how to do it
But believe me it was really easy, here you go:
Suppose if you are calling the following method in your controller:
$brands = Mage::getModel(’brands/brands’)->setData($data);
it means that you are calling the the brands.php in brands module model->Mysql4 folder.
Now in brands.php suppose we have category_ids field [...]

Get current url

This is a doozy but useful. Get the current URL anywhere in phtml or php files by using the core/url helper method.

$current_url = $this->helper(’core/url’)->getCurrentUrl();

How to add resource urls to CMS pages

Inside of magento cms pages
{{store direct_url=media}}

The given code snippet will produce http://www.example.com/media

Outside of magento cms pages
{{store direct_url=media/store/cms/brands/brand_logo.gif}}
The given code snippet will produce http://www.example.com/media/store/cms/brands/brand_logo.gif

Get image path

$this->getSkinUrl(’images/your_image_name.jpg’)
The code above would get the URL of the image “your_image_name.jpg” placed in your skin directory. Code works for both front and backend purposes. Hope it helps

Get base url in magento

<?php echo Mage::getBaseUrl(); ?>

How magento executes query?

Please go through with this tutorial:
http://framework.zend.com/manual/en/zend.db.select.html

Creating module/extention from start

Please follow this amazing link for tutorial:
http://t.wits.sg/2009/03/31/howto-repackageable-custom-extension-development-in-magento/