订房查询

Question

我在编写sql从表中获取可用空间时遇到问题。

我的表结构如下。

Table Booking
ID | START_DATE | END_DATE


Table BookingRoom (Intermediate Table)
ID   | BOOKING_ID   |ROOM_ID

一个房间可以链接到许多预订，一个预订可以包含很多房间

Table Room
Contains the ID room

我已经试过了，但是如果一个房间在两个不同的日期链接到两个不同的预订会比较麻烦，那么比较将只使用第一个预订ID进行。

SELECT DISTINCT r.ID FROM room AS r ,booking AS b,bookingroom AS br
 WHERE r.ID = br.ID_ROOM
 AND b.ID = br.ID_BOOKING
 AND (
           b.END_DATE < '05/14/2013'
        OR b.START_DATE > '05/15/2013'
     )

有人可以帮我编写SQL，以便在入住和退房之间获得可用的房间。

Answer 1

如果您想要的只是在所需日期的整个范围内可用的房间列表，那么类似以下的方法可能会起作用：

Select Room.Id
From Room
Where Room.Id Not In    (
                        Select RoomId
                        From BookingRoom
                            Join Booking
                                On Booking.Id = BookingRoom.BookingId
                        Where Booking.StartDate <= 'DesiredEndDate'
                            And Booking.EndDate >= 'DesiredStartDate'
                        )
Order By Room.Id

因此，使用原始示例，我们可能会得到：

Select Room.Id
From Room
Where Room.Id Not In    (
                        Select RoomId
                        From BookingRoom
                            Join Booking
                                On Booking.Id = BookingRoom.BookingId
                        Where Booking.StartDate <= '2013-05-15'
                            And Booking.EndDate >= '2013-05-14'
                        )
Order By Room.Id

Answer 2

您将要为“在X天进行的所有预订”定义一个清晰的记录集，然后使用外部联接来检索那些当天没有预订的房间。

SET @myDate = #someDay#
SELECT R.ID
FROM Room R
WHERE R.ID NOT IN (
    SELECT BR.ROOM_ID
    FROM BookingRoom BR
    INNER JOIN Booking B ON BR.Booking_ID = B.ID
    WHERE @myDate BETWEEN B.start_date and B.end_date
)

编辑：

由于您希望在预订期间使用所有开放式房间，因此您需要进行更复杂的查询。 我假设您已经将有问题的日期加载到外部，因为进行基于日期的多对多查询是PITA。

SET @dateStart = #Start#
SET @dateEnd = #End#

SELECT R.ID
FROM Room R
WHERE R.ID NOT IN (
    SELECT BR.ROOM_ID
    FROM BookingRoom BR
    INNER JOIN Booking B ON BR.Booking_ID = B.ID
    WHERE B.start_date BETWEEN @dateStart AND @dateEnd
    AND B.end_date BETWEEN @dateStart AND @dateEnd
)