Question

这些天我正努力学习酒店客房预订系统的学位课程。
现在我开始检查可用性阶段。
这是我的表结构

预订

`ID` int(11) 
`roomID` int(11)
`startDate` date 
`endDate` date

客房表

`roomID`    int(11)              
`name`  varchar(255)                     
`facilities`  mediumtext

想象一下有5个房间。 roomIDs是01,02,03,04和05。在这些房间，01预订。签到日期是05-11-2013＆amp;结帐日期是10-11-2013。

还有roomID 04，预订于2013年11月8日至2013年11月9日期间

如果用户检查从04-11-2013到10-11-2013的可用性，则仅显示房间ID 02,03和05。

如何建立一个显示结果的系统？

有人可以帮我构建SQL查询来检查可用性吗？

Answer 1

逻辑在这里实际上非常简单，你不需要任何开始和结束都在你的时期内的东西，或者它们在你正在寻找的范围内的任何一点的相对侧。

SELECT
    R.roomID,
    R.name,
    R.facilities
FROM
    -- Use the table rooms, but name it R for shorthand.
    Rooms R

    -- Left joins return null if there's no match, which we use in the where clause to identify these rows
    LEFT JOIN Bookings B
    -- B is bookings, R is rooms, they're aliased to make things easier
    ON B.RoomId = R.RoomId
        AND
        (
            -- As I said at the top of this answer, we want to exclude anything that matches any of 3 conditions:
            -- The start date is between the date's the room is already booked for
            @SearchCheckingStart BETWEEN B.startDate AND B.endDate
            OR
            -- The end date is in the period where the room is already booked
            @SearchCheckingEnd BETWEEN B.startDate AND B.endDate
            OR
            -- Or our date range lies between the period we're booking for
            B.startDate BETWEEN @SearchCheckingStart AND @SearchCheckingEnd
        )

    WHERE -- We're only interested in results where MySQL couldn't match the results earlier, this gives us the rooms that are free.
        B.RoomId IS NULL

检查可用性并列出可用房间

1 个答案: