Stuff

SELECT rcode.rcode_id, (

	SELECT SUM( pcode.pcode_points ) AS points
	FROM pcode
	WHERE pcode.rcode_id = rcode.rcode_id
) - (

	SELECT SUM( redemption.redemption_amount ) AS points
	FROM redemption
	WHERE redemption.rcode_id = rcode.rcode_id

)
FROM rcode