Today we wanted to work out which payment type had been used for a range of orders on the Ethical Shop. The quickest way I could think of was to dive into MariaDB/MySQL and issue a quesry on the sales_flat_order and sales_flat_order_payments tables for a range of orders.
You can use the increment_id field to specify the first and last orders that you are interested in, the method field tells you which payment type was used.
Here is the SQL you need to create the report with the most popular payment method first.
SELECT p.method, count(o.increment_id) AS num
FROM sales_flat_order AS o,
sales_flat_order_payment AS p
WHERE o.entity_id = p.parent_id
AND o.increment_id >= first_order_increment
AND o.increment_id <= last_order_increment
GROUP BY p.method
ORDER BY num desc;
Note that you will need to replace first_order_increment and last_order_increment with the first and last order increments. You can find these by looking at the order numbers that you are interested in the Magento backend.