<?php

$installer = $this;

$installer->startSetup();

$installer->run("

DROP TABLE IF EXISTS {$this->getTable('customer_manager')};
CREATE TABLE {$this->getTable('customer_manager')} (
  `manager_id` int(11) unsigned NOT NULL auto_increment,
  `title` varchar(255) NOT NULL default '',
  `email` varchar(255) NOT NULL default '',
  `password` varchar(255) NOT NULL default '',
  `parentuser_id` int(11) NOT NULL default ''
  PRIMARY KEY (`manager_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

");

$installer->endSetup();

class Excellence_Manager_Model_Entity_Customer extends Mage_Customer_Model_Resource_Customer {
public function loadByUsername(Mage_Customer_Model_Customer $customer, $username)
{

    try {
        $select = $this->_getReadAdapter()->select()
            ->from(array('c' => $this->getEntityTable()), array($this->getEntityIdField()))
            ->joinNatural(array('cev' => $this->getTable('customer_entity_varchar')))
            ->joinNatural(array('ea' => $this->getTable('eav/attribute')))
            ->joinLeft(array('mn' => $this->getTable('customer_manager')), 'mn.parentuser_id=c.entity_id')
            ->where('ea.attribute_code='username' AND cev.value=?',$username);
    }catch(Exception $ex)
    {
        echo $ex;
    }
    $this->load($customer, $id);
}