Magento Multi Database Guide

Here is a table showing major changes over the Magento version history:

| CE | PE | EE | Year | Major Changes ...

Magento CE 1.6 and PE/EE 1.11 introduced database abstraction, this is the way to set up tables using the new code.

$table = $installer->getConnection()
    ->newTable($installer->getTable('your_module/table_name_in_xml'))
    ->...

This site shows details of the Magento database schema for differing versions - it shows foreign key relationships in a nice drag-and-drop interface

This is a high-level view of the Magento Model, Resource Model and Resource Collection Model structure

If you have custom attributes named the same across multiple products, you
wish to remove said attributes, this might come in useful. The SQL below restricts
the removal of the attributes to a certain attribute set name, but you can remove
this is...

In /lib/Varien/Db/Adapter/Pdo/Mysql.php change this property to true:

/**
 * Write SQL debug data to file
 *
 * @var bool
 */
protected $_debug               = false;

To enable logging for queries slower than a certain ti...

To read:

Mage::getSingleton('core/resource')->getConnection('core_read');

To write:

Mage::getSingleton('core/resource')->getConnection('core_write');

The attached link describes everything fantastically, just go there.