SELECT	if (sp_interval = "day"
					,
						(
							SUM(
									(
										(
											TO_DAYS(LEAST(s_date_end, r_date_last))
											- TO_DAYS(GREATEST(r_date_from, s_date_start))
										) + 1
									 )   * sp_price
							)
						)
					,( ri_amount * ri_price )
			)	AS total_price

FROM 		reservations
INNER JOIN 	reservation_items
		ON 	ri_reservationsid = r_id
INNER JOIN 	products
		ON 	ri_productsid = p_id
INNER JOIN 	product_groups
		ON 	if( p_type = "house", p_house_public_productgroupsid, p_productgroupsid ) = pg_id
INNER JOIN 	season_prices
		ON 	sp_productgroupsid = pg_id
INNER JOIN 	seasons
		ON 	s_id = sp_seasonsid
WHERE 	( ri_id = 1 ) OR (ri_parentid = 1 )
		if (sp_interval = "day",
			(AND r_date_from <= s_date_end	AND r_date_last >= s_date_start )
			, ??
		)
group by	r_id