Cacher is the code snippet organizer for pro developers

require_once("app/Mage.php");
$app = Mage::app('');

$resource = Mage::getSingleton('core/resource');
$readConnection = $resource->getConnection('core_read');
$qTable   = $resource->getTableName('customer_entity');
$aTable   = $resource->getTableName('my_customers');

$query = 'SELECT * FROM  '.$qTable.'  q  left join '.$aTable.' a ON  a.customer_id=q.entity_id';
$results = $readConnection->fetchAll($query);

foreach($results as $result){
    echo  $result["email"].",".$result["my_id"].PHP_EOL;
}