Magento tutorial to work with product collections and databases

سؤال

looking for tutorial to work with product collections like,

Upsell products (just an example),
Grouping upsell products by categories,
accessing databases and get items by magento's MVC.

Sharing relevant tutorials is much appreciated.

المحلول

There are many tutorials available.

Start with these:

مرخصة بموجب: CC-BY-SA مع الإسناد

لا تنتمي إلى StackOverflow