Question

对于预订系统，我有一张房间，抵达和离开的桌子。

示例数据：

id | room | arrival    | departure
---+------+------------+-----------
1  | 1    | 2011-03-12 | 2011-03-14
2  | 1    | 2011-03-08 | 2011-03-09
3  | 1    | 2011-03-19 | 2011-03-20
4  | 2    | 2011-03-22 | 2011-03-30 
5  | 2    | 2011-03-19 | 2011-03-22

我现在的问题是：如果我有新的预订（2011-03-10到2011-03-12），我该如何查看哪些房间免费？

此示例的输出应为空间1和2。

Answer 1

这是一个查询，它将显示日期范围的非免费房间：

select room from bookings where
(arrival<'2011-03-12' and departure>='2011-03-12') -- overlap at the end
OR (arrival<='2011-03-10' and departure>'2011-03-10') -- overlap at the start
OR (arrival>='2011-03-10' and departure<='2011-03-12') -- complete overlap

您可以将其与

一起使用

select roomnumber from rooms where roomnumber not in (... as above ...)

找到免费房间

Answer 2

您也可以使用BETWEEN比较运算符来实现此目的。在这种情况下，你会做这样的事情：

SELECT r.id FROM room r WHERE r.id NOT IN
(
    SELECT rb.room FROM room_booking rb WHERE 
        ('2011-03-10' BETWEEN rb.arrival AND rb.departure) OR 
        ('2011-03-12' BETWEEN rb.arrival AND rb.departure)
)

寻找免费房间（预订系统）

2 个答案: