予約済みの部屋を選択して反転できます：
SELECT * FROM tbRoom WHERE RoomID NOT IN (SELECT RoomID FROM tbReservationDetail WHERE ArrvialDate < yourDate AND DepartureDate > yourDate)
予約済みの部屋を選択して反転できます：
SELECT * FROM tbRoom WHERE RoomID NOT IN (SELECT RoomID FROM tbReservationDetail WHERE ArrvialDate < yourDate AND DepartureDate > yourDate)
PHP/MySQL-ナビゲーションメニュー階層の構築 UPDATE table1 SET column1 =（SUM（table2 {＆table3} WHERE table2_id1 =id1）WHERE id1 =table2_id1