MySQL查詢問題：類似系統的保留

Question

房間可能有或沒有保留。 保留時間為（日期）至直到（日期）。 人員按日期搜索房間：from_field和till_field。 嘗試查找是否有房間。

SELECT rooms.* FROM rooms
LEFT JOIN reservations ON reservations.room_id = rooms.id
WHERE ( reservations.from > till_field OR reservations.till < from_field )

問題：如果單個預訂成功，則查詢似乎有可用的空間，即使另一個預訂占據了該位置。

Answer 1

如何檢索完全沒有保留的房間：

如果沒有保留，則查詢=>返回的沒有reservations行，您還必須檢查該行（ reservations.room_id IS NULL ）：

SELECT rooms.* FROM rooms
LEFT JOIN reservations ON reservations.room_id = rooms.id
WHERE reservations.room_id IS NULL -- if there is no reservations
      OR reservations.from > till_field
      OR reservations.till < from_field

但是要真正獲得想要的東西，您必須檢查沒有預訂的房間：

• fromDate or tillDate between from_field and till_field

OR

• fromDate < from_field and tillDate > till_field

SELECT rooms.*
  FROM rooms
 WHERE NOT EXISTS (SELECT NULL
                   FROM reservations 
                  WHERE reservations.room_id = rooms.id
                    AND ((
                          reservations.from BETWEEN from_field AND till_field
                          OR
                          reservations.till BETWEEN from_field AND till_field
                         )
                        OR
                         (
                          reservations.from < from_field
                          AND reservations.till > till_field
                         )
                        )
                  )