Magento 1.9 SQL – Direct SQL for New vs Existing Customers

I want to run an SQL query to show orders by new customers and existing customers and group them by month.

EDIT:

I now have this script however it only compares the dates if they are exact to the minute, I now need to compare the dates by just the date rather than date and time.

SELECT * 
FROM (

SELECT e.grand_total, e.created_at, COUNT( e.increment_id ) AS grand_total1, o.entity_id, o.created_at AS  `last_order_date` 
FROM  `mg_sales_flat_order` AS  `e` 
LEFT JOIN  `mg_customer_entity` AS  `o` ON e.customer_id = o.entity_id
WHERE e.created_at = o.created_at
GROUP BY YEAR( e.created_at ) , MONTH( e.created_at ) 
ORDER BY e.created_at DESC
)sub_query

Edit: to clarify I want a table to display:
Month – #New Customer Orders – #Existing Customer Orders – Total Customer Orders

A new customer would be a customer who came onto the site placed there first order in month x if they then came back and ordered in month a,b and c then those orders would be classed as existing customer orders

I have come across this script on this site but I'm not sure how that would help.

$LastOrder=Mage::getModel('sales/order')->load($orderId);
$LastOrdertime= $LastOrder->getCreatedAt();

$OrderCollection=Mage::getModel('sales/order')->getCollection()->addFieldToFilter('customer_email',$LastOrder->getData('customer_email'))
        ->setOrder('created_at','asc');
$fstoredetime= $OrderCollection->getFirstItem()->getCreatedAt();    

if($fstoredetime==$LastOrdertime):
// new customer
else:
//old customer
endif;  

I can get number of transactions by month with this code but I want to split it out into new and existing customers

<?php
            $result = mysqli_query($con,"SELECT count(*), created_at FROM sales_flat_order WHERE status NOT LIKE 'canceled' AND store_id BETWEEN 1 AND 2 GROUP BY YEAR(created_at), MONTH(created_at) ORDER BY created_at DESC");

            while($row = mysqli_fetch_array($result)) {

            $num = $row[0];

              echo "<tr>";

              echo "<td>";

              echo date("m/Y", strtotime($row['created_at']));

              echo "</td>";

              echo "<td>";

              echo $num;

              echo "</td>";

              echo "</tr>";
            }

            mysqli_close($con);
        ?>

I have also tried comparing created_at in both customer and order tables, has anyone done this before?

SOLUTION:

SELECT * 
FROM (
SELECT e.grand_total, e.created_at, COUNT( e.increment_id ) AS grand_total1, o.entity_id, o.created_at AS  `last_order_date` 
FROM  `mg_sales_flat_order` AS  `e` 
LEFT JOIN  `mg_customer_entity` AS  `o` ON e.customer_id = o.entity_id
WHERE DATE(e.created_at) = DATE(o.created_at)
GROUP BY YEAR( e.created_at ) , MONTH( e.created_at ) 
ORDER BY created_at DESC
)sub_query

I also found more information here http://www.webamondo.co.uk/blog/magento-sql-repeat-customers-vs-new-customers/