SELECT r_id, (
TO_DAYS( LEAST( s_date_end, r_date_last ) ) - TO_DAYS( GREATEST( r_date_from, s_date_start ) ) + if( r_date_last > s_date_end, 1, 0 )
) AS total_days, s_date_start, s_date_end, r_date_from, r_date_last
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
AND r_date_from <= s_date_end
AND r_date_last >= s_date_start
WHERE (
ri_parentid =0
OR ri_parentid IS NULL
)
AND ri_id =1