[Magento] Create a simple report

1)get the tablse schema;

describe sales_flat_order;

show columns from sales_flat_order;

2)write the SQL

selecttt.customer_group_code,tt.name,sum(tt.total_qty_ordered)from<wbr></wbr>

(selectc.customer_group_code,t.coupon_code,t.total_qty_ordered,t.grand_total,s.name<wbr></wbr>

from sales_flat_order t inner join sales_flat_order_item s ont.entity_id = s.order_id inner join customer_group c ont.customer_group_id = c.customer_group_id) tt group bytt.customer_group_code,tt.name

3) write the codes;

$resource = Mage::getSingleton('core/resource');

$connection = $resource->getConnection('core_read');

$sql = " above SQL";

$results = $connection->fetchAll($sql);