Question

有可能有或没有预订的房间。预订从（日期）到（日期）。人员按日期搜索房间：from_field和till_field。试着找一个房间是否可用。

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

问题：如果单个预订成功，则查询似乎具有可用空间，即使另一个预留占据该位置。

Answer 1

如何检索没有重新开始的房间：

如果没有预订，查询将返回reservations行=＆gt;您还必须检查（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

但要真正得到你想要的东西，你必须检查没有任何预订的房间：

<子>

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
                         )
                        )
                  )

MySQL查询问题：像系统一样预留

1 个答案: