Pretend - sign before disocunt amount

UPDATE numestaging.sales_flat_order SET base_discount_amount = CONCAT('-',base_discount_amount)  WHERE `coupon_code` LIKE '%couponcode%' ORDER BY `entity_id`

UPDATE numestaging.sales_flat_order SET base_discount_amount = CONCAT('-',base_discount_amount) WHERE `base_discount_amount` > 0

SELECT * FROM sales_flat_order WHERE `base_discount_amount` > 0