title: Explain magento database structure
body: <p>I am trying to learn magento framework. But it is hard to understand the database structure. So I am looking for a document that describe what each table exactly do and explain each column in that table. I have searched on google but all I found was magento database structure without any describes (table and column) <a href="http://www.magentocommerce.com/wiki/2_-_magento_concepts_and_architecture/magento_database_diagram" rel="noreferrer">Magento Database Diagram</a></p>
  
  <p>ex:
  the field <code>converted_at</code> in <code>sales_flat_quote</code> table. I have no idea what this field do.</p>
  
  <p>What I looking for is like this topic <a href="http://excellencemagentoblog.com/blog/2011/09/07/magento-eav-database-structure/" rel="noreferrer">excellencemagentoblog.com: Magento EAV Database Structure</a> but it is only describe  eav table</p>
  
  <p>ps: so sorry because my bad english</p>