SELECT
r.id_reservation,
CONCAT(c.firstname, ' ', c.lastname, ', ', c.street, ' ', c.number, ', ', c.zip, ' ', c.city) AS customer,
r.`from`, 
r.until, 
r.adults, 
r.childs_over_2 AS childs, 
r.childs_under_2 AS babies, 
r.price_season, 
r.price_special,
CASE WHEN r.price_special <> 0 THEN r.price_special
ELSE ROUND((
	r.price_season +
	(
		(SELECT price FROM extras WHERE id_extras = 8) * r.adults * DATEDIFF(until, `from`) +
		(SELECT price FROM extras WHERE id_extras = 9) * r.childs_over_2 * DATEDIFF(until, `from`) +
		(SELECT price FROM extras WHERE id_extras = 10) * r.childs_under_2 * DATEDIFF(until, `from`)
	) +
	SUM(
		CASE WHEN UPPER(e.turnus) = 'EINMALIG' THEN e.price ELSE e.price * DATEDIFF(until, `from`) END
	)
), 2) END AS endprice, 
r.prepay, 
r.caution, 
r.storno, 
r.comment, 
r.payment, 
f.f_number AS flat, 
GROUP_CONCAT(e.extra SEPARATOR ', ') AS extras
FROM reservation r
JOIN reservation_extras re USING (id_reservation)
JOIN extras e USING (id_extras)
JOIN flats f USING (id_flats)
JOIN customer c USING(id_customer)
WHERE e.id_extras NOT IN (8, 9, 10)
GROUP BY r.id_reservation